diff --git a/.gitignore b/.gitignore
index 9e7e900d..dfe85986 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,4 +3,5 @@ node_modules
 coverage
 .DS_Store
 dist
-.vscode
\ No newline at end of file
+.vscode
+.claude
\ No newline at end of file
diff --git a/.prettierrc b/.prettierrc
new file mode 100644
index 00000000..58085c20
--- /dev/null
+++ b/.prettierrc
@@ -0,0 +1,7 @@
+{
+	"useTabs": true,
+	"singleQuote": true,
+	"trailingComma": "all",
+	"semi": false,
+	"printWidth": 140
+}
\ No newline at end of file
diff --git a/package-lock.json b/package-lock.json
index 57fa46ab..ce2c12aa 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -14,10 +14,14 @@
       },
       "devDependencies": {
         "@codecov/vite-plugin": "^1.9.0",
+        "@types/css-tree": "^2.3.11",
         "c8": "^10.1.3",
+        "prettier": "^3.6.2",
+        "typescript": "^5.9.3",
         "uvu": "^0.5.6",
         "vite": "^6.3.4",
-        "vite-plugin-dts": "^4.5.0"
+        "vite-plugin-dts": "^4.5.0",
+        "vitest": "^4.0.8"
       },
       "engines": {
         "node": ">=18.0.0"
@@ -740,9 +744,9 @@
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-      "resolved": "https://registry.npmjs.org/@jridgewell/sourcemap-codec/-/sourcemap-codec-1.5.0.tgz",
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+      "version": "1.5.5",
+      "resolved": "https://registry.npmjs.org/@jridgewell/sourcemap-codec/-/sourcemap-codec-1.5.5.tgz",
+      "integrity": "sha512-cYQ9310grqxueWbl+WuIUIaiUaDcj7WOq5fVhEljNVgRfOUhY9fy2zTvfoqWsnebh8Sl70VScFbICvJnLKB0Og==",
       "dev": true,
       "license": "MIT"
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@@ -896,6 +900,7 @@
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       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@octokit/auth-token": "^4.0.0",
         "@octokit/graphql": "^7.1.0",
@@ -1496,6 +1501,13 @@
         "string-argv": "~0.3.1"
       }
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+    "node_modules/@standard-schema/spec": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/@standard-schema/spec/-/spec-1.0.0.tgz",
+      "integrity": "sha512-m2bOd0f2RT9k8QJx1JN85cZYyH1RqFBdlwtkSlf4tBDYLCiiZnv1fIIwacK6cqwXavOydf0NPToMQgpKq+dVlA==",
+      "dev": true,
+      "license": "MIT"
+    },
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       "version": "1.0.38",
       "resolved": "https://registry.npmjs.org/@types/argparse/-/argparse-1.0.38.tgz",
@@ -1503,6 +1515,31 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/@types/chai": {
+      "version": "5.2.3",
+      "resolved": "https://registry.npmjs.org/@types/chai/-/chai-5.2.3.tgz",
+      "integrity": "sha512-Mw558oeA9fFbv65/y4mHtXDs9bPnFMZAL/jxdPFUpOHHIXX91mcgEHbS5Lahr+pwZFR8A7GQleRWeI6cGFC2UA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@types/deep-eql": "*",
+        "assertion-error": "^2.0.1"
+      }
+    },
+    "node_modules/@types/css-tree": {
+      "version": "2.3.11",
+      "resolved": "https://registry.npmjs.org/@types/css-tree/-/css-tree-2.3.11.tgz",
+      "integrity": "sha512-aEokibJOI77uIlqoBOkVbaQGC9zII0A+JH1kcTNKW2CwyYWD8KM6qdo+4c77wD3wZOQfJuNWAr9M4hdk+YhDIg==",
+      "dev": true,
+      "license": "MIT"
+    },
+    "node_modules/@types/deep-eql": {
+      "version": "4.0.2",
+      "resolved": "https://registry.npmjs.org/@types/deep-eql/-/deep-eql-4.0.2.tgz",
+      "integrity": "sha512-c9h9dVVMigMPc4bwTvC5dxqtqJZwQPePsWjPlpSOnojbor6pGqdk541lfA7AqFQr5pB1BRdq0juY9db81BwyFw==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/@types/estree": {
       "version": "1.0.7",
       "resolved": "https://registry.npmjs.org/@types/estree/-/estree-1.0.7.tgz",
@@ -1517,6 +1554,127 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/@vitest/expect": {
+      "version": "4.0.8",
+      "resolved": "https://registry.npmjs.org/@vitest/expect/-/expect-4.0.8.tgz",
+      "integrity": "sha512-Rv0eabdP/xjAHQGr8cjBm+NnLHNoL268lMDK85w2aAGLFoVKLd8QGnVon5lLtkXQCoYaNL0wg04EGnyKkkKhPA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@standard-schema/spec": "^1.0.0",
+        "@types/chai": "^5.2.2",
+        "@vitest/spy": "4.0.8",
+        "@vitest/utils": "4.0.8",
+        "chai": "^6.2.0",
+        "tinyrainbow": "^3.0.3"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      }
+    },
+    "node_modules/@vitest/mocker": {
+      "version": "4.0.8",
+      "resolved": "https://registry.npmjs.org/@vitest/mocker/-/mocker-4.0.8.tgz",
+      "integrity": "sha512-9FRM3MZCedXH3+pIh+ME5Up2NBBHDq0wqwhOKkN4VnvCiKbVxddqH9mSGPZeawjd12pCOGnl+lo/ZGHt0/dQSg==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@vitest/spy": "4.0.8",
+        "estree-walker": "^3.0.3",
+        "magic-string": "^0.30.21"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      },
+      "peerDependencies": {
+        "msw": "^2.4.9",
+        "vite": "^6.0.0 || ^7.0.0-0"
+      },
+      "peerDependenciesMeta": {
+        "msw": {
+          "optional": true
+        },
+        "vite": {
+          "optional": true
+        }
+      }
+    },
+    "node_modules/@vitest/mocker/node_modules/estree-walker": {
+      "version": "3.0.3",
+      "resolved": "https://registry.npmjs.org/estree-walker/-/estree-walker-3.0.3.tgz",
+      "integrity": "sha512-7RUKfXgSMMkzt6ZuXmqapOurLGPPfgj6l9uRZ7lRGolvk0y2yocc35LdcxKC5PQZdn2DMqioAQ2NoWcrTKmm6g==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@types/estree": "^1.0.0"
+      }
+    },
+    "node_modules/@vitest/pretty-format": {
+      "version": "4.0.8",
+      "resolved": "https://registry.npmjs.org/@vitest/pretty-format/-/pretty-format-4.0.8.tgz",
+      "integrity": "sha512-qRrjdRkINi9DaZHAimV+8ia9Gq6LeGz2CgIEmMLz3sBDYV53EsnLZbJMR1q84z1HZCMsf7s0orDgZn7ScXsZKg==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "tinyrainbow": "^3.0.3"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      }
+    },
+    "node_modules/@vitest/runner": {
+      "version": "4.0.8",
+      "resolved": "https://registry.npmjs.org/@vitest/runner/-/runner-4.0.8.tgz",
+      "integrity": "sha512-mdY8Sf1gsM8hKJUQfiPT3pn1n8RF4QBcJYFslgWh41JTfrK1cbqY8whpGCFzBl45LN028g0njLCYm0d7XxSaQQ==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@vitest/utils": "4.0.8",
+        "pathe": "^2.0.3"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      }
+    },
+    "node_modules/@vitest/snapshot": {
+      "version": "4.0.8",
+      "resolved": "https://registry.npmjs.org/@vitest/snapshot/-/snapshot-4.0.8.tgz",
+      "integrity": "sha512-Nar9OTU03KGiubrIOFhcfHg8FYaRaNT+bh5VUlNz8stFhCZPNrJvmZkhsr1jtaYvuefYFwK2Hwrq026u4uPWCw==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@vitest/pretty-format": "4.0.8",
+        "magic-string": "^0.30.21",
+        "pathe": "^2.0.3"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      }
+    },
+    "node_modules/@vitest/spy": {
+      "version": "4.0.8",
+      "resolved": "https://registry.npmjs.org/@vitest/spy/-/spy-4.0.8.tgz",
+      "integrity": "sha512-nvGVqUunyCgZH7kmo+Ord4WgZ7lN0sOULYXUOYuHr55dvg9YvMz3izfB189Pgp28w0vWFbEEfNc/c3VTrqrXeA==",
+      "dev": true,
+      "license": "MIT",
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      }
+    },
+    "node_modules/@vitest/utils": {
+      "version": "4.0.8",
+      "resolved": "https://registry.npmjs.org/@vitest/utils/-/utils-4.0.8.tgz",
+      "integrity": "sha512-pdk2phO5NDvEFfUTxcTP8RFYjVj/kfLSPIN5ebP2Mu9kcIMeAQTbknqcFEyBcC4z2pJlJI9aS5UQjcYfhmKAow==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@vitest/pretty-format": "4.0.8",
+        "tinyrainbow": "^3.0.3"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      }
+    },
     "node_modules/@volar/language-core": {
       "version": "2.4.11",
       "resolved": "https://registry.npmjs.org/@volar/language-core/-/language-core-2.4.11.tgz",
@@ -1720,6 +1878,16 @@
         "sprintf-js": "~1.0.2"
       }
     },
+    "node_modules/assertion-error": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/assertion-error/-/assertion-error-2.0.1.tgz",
+      "integrity": "sha512-Izi8RQcffqCeNVgFigKli1ssklIbpHnCYc6AknXGYoB6grJqyeby7jv12JUQgmTAnIDnbck1uxksT4dzN3PWBA==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=12"
+      }
+    },
     "node_modules/balanced-match": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-1.0.2.tgz",
@@ -1843,6 +2011,16 @@
         "url": "https://github.com/sponsors/sindresorhus"
       }
     },
+    "node_modules/chai": {
+      "version": "6.2.0",
+      "resolved": "https://registry.npmjs.org/chai/-/chai-6.2.0.tgz",
+      "integrity": "sha512-aUTnJc/JipRzJrNADXVvpVqi6CO0dn3nx4EVPxijri+fj3LUUDyZQOgVeW54Ob3Y1Xh9Iz8f+CgaCl8v0mn9bA==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=18"
+      }
+    },
     "node_modules/chalk": {
       "version": "4.1.2",
       "resolved": "https://registry.npmjs.org/chalk/-/chalk-4.1.2.tgz",
@@ -1952,9 +2130,9 @@
       "license": "MIT"
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-      "resolved": "https://registry.npmjs.org/debug/-/debug-4.4.0.tgz",
-      "integrity": "sha512-6WTZ/IxCY/T6BALoZHaE4ctp9xm+Z5kY/pzYaCHRFeyVhojxlrm+46y68HA6hr0TcwEssoxNiDEUJQjfPZ/RYA==",
+      "version": "4.4.3",
+      "resolved": "https://registry.npmjs.org/debug/-/debug-4.4.3.tgz",
+      "integrity": "sha512-RGwwWnwQvkVfavKVt22FGLw+xYSdzARwm0ru6DhTVA3umU5hZc28V3kO4stgYryrTlLpuvgI9GiijltAjNbcqA==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
@@ -2019,6 +2197,13 @@
         "url": "https://github.com/fb55/entities?sponsor=1"
       }
     },
+    "node_modules/es-module-lexer": {
+      "version": "1.7.0",
+      "resolved": "https://registry.npmjs.org/es-module-lexer/-/es-module-lexer-1.7.0.tgz",
+      "integrity": "sha512-jEQoCwk8hyb2AZziIOLhDqpm5+2ww5uIE6lkO/6jcOCusfk6LhMHpXXfBLXTZ7Ydyt0j4VoUQv6uGNYbdW+kBA==",
+      "dev": true,
+      "license": "MIT"
+    },
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       "resolved": "https://registry.npmjs.org/esbuild/-/esbuild-0.25.1.tgz",
@@ -2075,6 +2260,16 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/expect-type": {
+      "version": "1.2.2",
+      "resolved": "https://registry.npmjs.org/expect-type/-/expect-type-1.2.2.tgz",
+      "integrity": "sha512-JhFGDVJ7tmDJItKhYgJCGLOWjuK9vPxiXoUFLwLDc99NlmklilbiQJwoctZtt13+xMw91MCk/REan6MWHqDjyA==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "engines": {
+        "node": ">=12.0.0"
+      }
+    },
     "node_modules/fast-deep-equal": {
       "version": "3.1.3",
       "resolved": "https://registry.npmjs.org/fast-deep-equal/-/fast-deep-equal-3.1.3.tgz",
@@ -2083,11 +2278,14 @@
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-      "integrity": "sha512-1NZP+GK4GfuAv3PqKvxQRDMjdSRZjnkq7KfhlNrCNNlZ0ygQFpebfrnfnq/W7fpUnAv9aGWmY1zKx7FYL3gwhg==",
+      "version": "6.5.0",
+      "resolved": "https://registry.npmjs.org/fdir/-/fdir-6.5.0.tgz",
+      "integrity": "sha512-tIbYtZbucOs0BRGqPJkshJUYdL+SDH7dVM8gjy+ERp3WAUjLEFJE+02kanyHtwjWOnwrKYBiwAmM0p4kLJAnXg==",
       "dev": true,
       "license": "MIT",
+      "engines": {
+        "node": ">=12.0.0"
+      },
       "peerDependencies": {
         "picomatch": "^3 || ^4"
       },
@@ -2418,13 +2616,13 @@
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-      "resolved": "https://registry.npmjs.org/magic-string/-/magic-string-0.30.17.tgz",
-      "integrity": "sha512-sNPKHvyjVf7gyjwS4xGTaW/mCnF8wnjtifKBEhxfZ7E/S8tQ0rssrwGNn6q8JH/ohItJfSQp9mBtQYuTlH5QnA==",
+      "version": "0.30.21",
+      "resolved": "https://registry.npmjs.org/magic-string/-/magic-string-0.30.21.tgz",
+      "integrity": "sha512-vd2F4YUyEXKGcLHoq+TEyCjxueSeHnFxyyjNp80yg0XV4vUhnDer/lvvlqM/arB5bXQN5K2/3oinyCRyx8T2CQ==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "@jridgewell/sourcemap-codec": "^1.5.0"
+        "@jridgewell/sourcemap-codec": "^1.5.5"
       }
     },
     "node_modules/mdn-data": {
@@ -2595,9 +2793,9 @@
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-      "resolved": "https://registry.npmjs.org/picomatch/-/picomatch-4.0.2.tgz",
-      "integrity": "sha512-M7BAV6Rlcy5u+m6oPhAPFgJTzAioX/6B0DxyvDlo9l8+T3nLKbrczg2WLUyzd45L8RqfUMyGPzekbMvX2Ldkwg==",
+      "version": "4.0.3",
+      "resolved": "https://registry.npmjs.org/picomatch/-/picomatch-4.0.3.tgz",
+      "integrity": "sha512-5gTmgEY/sqK6gFXLIsQNH19lWb4ebPDLA4SdLP7dsWkIXHWlG66oPuVvXSGFPppYZz8ZDZq0dYYrbHfBCVUb1Q==",
       "dev": true,
       "license": "MIT",
       "engines": {
@@ -2648,6 +2846,22 @@
         "node": "^10 || ^12 || >=14"
       }
     },
+    "node_modules/prettier": {
+      "version": "3.6.2",
+      "resolved": "https://registry.npmjs.org/prettier/-/prettier-3.6.2.tgz",
+      "integrity": "sha512-I7AIg5boAr5R0FFtJ6rCfD+LFsWHp81dolrFD8S79U9tb8Az2nGrJncnMSnys+bpQJfRUzqs9hnA81OAA3hCuQ==",
+      "dev": true,
+      "license": "MIT",
+      "bin": {
+        "prettier": "bin/prettier.cjs"
+      },
+      "engines": {
+        "node": ">=14"
+      },
+      "funding": {
+        "url": "https://github.com/prettier/prettier?sponsor=1"
+      }
+    },
     "node_modules/punycode": {
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       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@types/estree": "1.0.7"
       },
@@ -2785,6 +3000,13 @@
         "node": ">=8"
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+    "node_modules/siginfo": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/siginfo/-/siginfo-2.0.0.tgz",
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+      "dev": true,
+      "license": "ISC"
+    },
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@@ -2823,6 +3045,20 @@
       "dev": true,
       "license": "BSD-3-Clause"
     },
+    "node_modules/stackback": {
+      "version": "0.0.2",
+      "resolved": "https://registry.npmjs.org/stackback/-/stackback-0.0.2.tgz",
+      "integrity": "sha512-1XMJE5fQo1jGH6Y/7ebnwPOBEkIEnT4QF32d5R1+VXdXveM0IBMJt8zfaxX1P3QhVwrYe+576+jkANtSS2mBbw==",
+      "dev": true,
+      "license": "MIT"
+    },
+    "node_modules/std-env": {
+      "version": "3.10.0",
+      "resolved": "https://registry.npmjs.org/std-env/-/std-env-3.10.0.tgz",
+      "integrity": "sha512-5GS12FdOZNliM5mAOxFRg7Ir0pWz8MdpYm6AY6VPkGpbA7ZzmbzNcBJQ0GPvvyWgcY7QAhCgf9Uy89I03faLkg==",
+      "dev": true,
+      "license": "MIT"
+    },
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       "resolved": "https://registry.npmjs.org/string-argv/-/string-argv-0.3.2.tgz",
@@ -2945,15 +3181,29 @@
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       }
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+    "node_modules/tinybench": {
+      "version": "2.9.0",
+      "resolved": "https://registry.npmjs.org/tinybench/-/tinybench-2.9.0.tgz",
+      "integrity": "sha512-0+DUvqWMValLmha6lr4kD8iAMK1HzV0/aKnCtWb9v9641TnP/MFb7Pc2bxoxQjTXAErryXVgUOfv2YqNllqGeg==",
+      "dev": true,
+      "license": "MIT"
+    },
+    "node_modules/tinyexec": {
+      "version": "0.3.2",
+      "resolved": "https://registry.npmjs.org/tinyexec/-/tinyexec-0.3.2.tgz",
+      "integrity": "sha512-KQQR9yN7R5+OSwaK0XQoj22pwHoTlgYqmUscPYoknOoWCWfj/5/ABTMRi69FrKU5ffPVh5QcFikpWJI/P1ocHA==",
+      "dev": true,
+      "license": "MIT"
+    },
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-      "resolved": "https://registry.npmjs.org/tinyglobby/-/tinyglobby-0.2.13.tgz",
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+    "prettier": {
+      "version": "3.6.2",
+      "resolved": "https://registry.npmjs.org/prettier/-/prettier-3.6.2.tgz",
+      "integrity": "sha512-I7AIg5boAr5R0FFtJ6rCfD+LFsWHp81dolrFD8S79U9tb8Az2nGrJncnMSnys+bpQJfRUzqs9hnA81OAA3hCuQ==",
+      "dev": true
+    },
     "punycode": {
       "version": "2.3.1",
       "resolved": "https://registry.npmjs.org/punycode/-/punycode-2.3.1.tgz",
@@ -5019,6 +5516,7 @@
       "resolved": "https://registry.npmjs.org/rollup/-/rollup-4.40.1.tgz",
       "integrity": "sha512-C5VvvgCCyfyotVITIAv+4efVytl5F7wt+/I2i9q9GZcEXW9BP52YYOXC58igUi+LFZVHukErIIqQSWwv/M3WRw==",
       "dev": true,
+      "peer": true,
       "requires": {
         "@rollup/rollup-android-arm-eabi": "4.40.1",
         "@rollup/rollup-android-arm64": "4.40.1",
@@ -5072,6 +5570,12 @@
       "integrity": "sha512-7++dFhtcx3353uBaq8DDR4NuxBetBzC7ZQOhmTQInHEd6bSrXdiEyzCvG07Z44UYdLShWUyXt5M/yhz8ekcb1A==",
       "dev": true
     },
+    "siginfo": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/siginfo/-/siginfo-2.0.0.tgz",
+      "integrity": "sha512-ybx0WO1/8bSBLEWXZvEd7gMW3Sn3JFlW3TvX1nREbDLRNQNaeNN8WK0meBwPdAaOI7TtRRRJn/Es1zhrrCHu7g==",
+      "dev": true
+    },
     "signal-exit": {
       "version": "4.1.0",
       "resolved": "https://registry.npmjs.org/signal-exit/-/signal-exit-4.1.0.tgz",
@@ -5095,6 +5599,18 @@
       "integrity": "sha512-D9cPgkvLlV3t3IzL0D0YLvGA9Ahk4PcvVwUbN0dSGr1aP0Nrt4AEnTUbuGvquEC0mA64Gqt1fzirlRs5ibXx8g==",
       "dev": true
     },
+    "stackback": {
+      "version": "0.0.2",
+      "resolved": "https://registry.npmjs.org/stackback/-/stackback-0.0.2.tgz",
+      "integrity": "sha512-1XMJE5fQo1jGH6Y/7ebnwPOBEkIEnT4QF32d5R1+VXdXveM0IBMJt8zfaxX1P3QhVwrYe+576+jkANtSS2mBbw==",
+      "dev": true
+    },
+    "std-env": {
+      "version": "3.10.0",
+      "resolved": "https://registry.npmjs.org/std-env/-/std-env-3.10.0.tgz",
+      "integrity": "sha512-5GS12FdOZNliM5mAOxFRg7Ir0pWz8MdpYm6AY6VPkGpbA7ZzmbzNcBJQ0GPvvyWgcY7QAhCgf9Uy89I03faLkg==",
+      "dev": true
+    },
     "string-argv": {
       "version": "0.3.2",
       "resolved": "https://registry.npmjs.org/string-argv/-/string-argv-0.3.2.tgz",
@@ -5173,16 +5689,34 @@
         "minimatch": "^9.0.4"
       }
     },
+    "tinybench": {
+      "version": "2.9.0",
+      "resolved": "https://registry.npmjs.org/tinybench/-/tinybench-2.9.0.tgz",
+      "integrity": "sha512-0+DUvqWMValLmha6lr4kD8iAMK1HzV0/aKnCtWb9v9641TnP/MFb7Pc2bxoxQjTXAErryXVgUOfv2YqNllqGeg==",
+      "dev": true
+    },
+    "tinyexec": {
+      "version": "0.3.2",
+      "resolved": "https://registry.npmjs.org/tinyexec/-/tinyexec-0.3.2.tgz",
+      "integrity": "sha512-KQQR9yN7R5+OSwaK0XQoj22pwHoTlgYqmUscPYoknOoWCWfj/5/ABTMRi69FrKU5ffPVh5QcFikpWJI/P1ocHA==",
+      "dev": true
+    },
     "tinyglobby": {
-      "version": "0.2.13",
-      "resolved": "https://registry.npmjs.org/tinyglobby/-/tinyglobby-0.2.13.tgz",
-      "integrity": "sha512-mEwzpUgrLySlveBwEVDMKk5B57bhLPYovRfPAXD5gA/98Opn0rCDj3GtLwFvCvH5RK9uPCExUROW5NjDwvqkxw==",
+      "version": "0.2.15",
+      "resolved": "https://registry.npmjs.org/tinyglobby/-/tinyglobby-0.2.15.tgz",
+      "integrity": "sha512-j2Zq4NyQYG5XMST4cbs02Ak8iJUdxRM0XI5QyxXuZOzKOINmWurp3smXu3y5wDcJrptwpSjgXHzIQxR0omXljQ==",
       "dev": true,
       "requires": {
-        "fdir": "^6.4.4",
-        "picomatch": "^4.0.2"
+        "fdir": "^6.5.0",
+        "picomatch": "^4.0.3"
       }
     },
+    "tinyrainbow": {
+      "version": "3.0.3",
+      "resolved": "https://registry.npmjs.org/tinyrainbow/-/tinyrainbow-3.0.3.tgz",
+      "integrity": "sha512-PSkbLUoxOFRzJYjjxHJt9xro7D+iilgMX/C9lawzVuYiIdcihh9DXmVibBe8lmcFrRi/VzlPjBxbN7rH24q8/Q==",
+      "dev": true
+    },
     "tunnel": {
       "version": "0.0.6",
       "resolved": "https://registry.npmjs.org/tunnel/-/tunnel-0.0.6.tgz",
@@ -5190,9 +5724,9 @@
       "dev": true
     },
     "typescript": {
-      "version": "5.7.3",
-      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.7.3.tgz",
-      "integrity": "sha512-84MVSjMEHP+FQRPy3pX9sTVV/INIex71s9TL2Gm5FG/WG1SqXeKyZ0k7/blY/4FdOzI12CBy1vGc4og/eus0fw==",
+      "version": "5.9.3",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.9.3.tgz",
+      "integrity": "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw==",
       "dev": true,
       "peer": true
     },
@@ -5278,6 +5812,7 @@
       "resolved": "https://registry.npmjs.org/vite/-/vite-6.4.1.tgz",
       "integrity": "sha512-+Oxm7q9hDoLMyJOYfUYBuHQo+dkAloi33apOPP56pzj+vsdJDzr+j1NISE5pyaAuKL4A3UD34qd0lx5+kfKp2g==",
       "dev": true,
+      "peer": true,
       "requires": {
         "esbuild": "^0.25.0",
         "fdir": "^6.4.4",
@@ -5305,6 +5840,34 @@
         "magic-string": "^0.30.17"
       }
     },
+    "vitest": {
+      "version": "4.0.8",
+      "resolved": "https://registry.npmjs.org/vitest/-/vitest-4.0.8.tgz",
+      "integrity": "sha512-urzu3NCEV0Qa0Y2PwvBtRgmNtxhj5t5ULw7cuKhIHh3OrkKTLlut0lnBOv9qe5OvbkMH2g38G7KPDCTpIytBVg==",
+      "dev": true,
+      "requires": {
+        "@vitest/expect": "4.0.8",
+        "@vitest/mocker": "4.0.8",
+        "@vitest/pretty-format": "4.0.8",
+        "@vitest/runner": "4.0.8",
+        "@vitest/snapshot": "4.0.8",
+        "@vitest/spy": "4.0.8",
+        "@vitest/utils": "4.0.8",
+        "debug": "^4.4.3",
+        "es-module-lexer": "^1.7.0",
+        "expect-type": "^1.2.2",
+        "magic-string": "^0.30.21",
+        "pathe": "^2.0.3",
+        "picomatch": "^4.0.3",
+        "std-env": "^3.10.0",
+        "tinybench": "^2.9.0",
+        "tinyexec": "^0.3.2",
+        "tinyglobby": "^0.2.15",
+        "tinyrainbow": "^3.0.3",
+        "vite": "^6.0.0 || ^7.0.0",
+        "why-is-node-running": "^2.3.0"
+      }
+    },
     "vscode-uri": {
       "version": "3.1.0",
       "resolved": "https://registry.npmjs.org/vscode-uri/-/vscode-uri-3.1.0.tgz",
@@ -5326,6 +5889,16 @@
         "isexe": "^2.0.0"
       }
     },
+    "why-is-node-running": {
+      "version": "2.3.0",
+      "resolved": "https://registry.npmjs.org/why-is-node-running/-/why-is-node-running-2.3.0.tgz",
+      "integrity": "sha512-hUrmaWBdVDcxvYqnyh09zunKzROWjbZTiNy8dBEjkS7ehEDQibXJ7XvlmtbwuTclUiIyN+CyXQD4Vmko8fNm8w==",
+      "dev": true,
+      "requires": {
+        "siginfo": "^2.0.0",
+        "stackback": "0.0.2"
+      }
+    },
     "wrap-ansi": {
       "version": "7.0.0",
       "resolved": "https://registry.npmjs.org/wrap-ansi/-/wrap-ansi-7.0.0.tgz",
diff --git a/package.json b/package.json
index f24b3404..f1ff7916 100644
--- a/package.json
+++ b/package.json
@@ -24,7 +24,8 @@
     "node": ">=18.0.0"
   },
   "scripts": {
-    "test": "uvu",
+    "test": "vitest",
+    "check": "tsc --noEmit",
     "build": "vite build"
   },
   "keywords": [
@@ -50,9 +51,13 @@
   },
   "devDependencies": {
     "@codecov/vite-plugin": "^1.9.0",
+    "@types/css-tree": "^2.3.11",
     "c8": "^10.1.3",
+    "prettier": "^3.6.2",
+    "typescript": "^5.9.3",
     "uvu": "^0.5.6",
     "vite": "^6.3.4",
-    "vite-plugin-dts": "^4.5.0"
+    "vite-plugin-dts": "^4.5.0",
+    "vitest": "^4.0.8"
   }
-}
\ No newline at end of file
+}
diff --git a/src/aggregate-collection.js b/src/aggregate-collection.js
deleted file mode 100644
index 190cae8a..00000000
--- a/src/aggregate-collection.js
+++ /dev/null
@@ -1,99 +0,0 @@
-/**
- * Find the mode (most occurring value) in an array of Numbers
- * Takes the mean/average of multiple values if multiple values occur the same amount of times.
- *
- * @see https://github.com/angus-c/just/blob/684af9ca0c7808bc78543ec89379b1fdfce502b1/packages/array-mode/index.js
- * @param {Array} arr - Array to find the mode value for
- * @returns {Number} mode - The `mode` value of `arr`
- */
-function Mode(arr) {
-  let frequencies = new Map()
-  let maxOccurrences = -1
-  let maxOccurenceCount = 0
-  let sum = 0
-  let len = arr.length
-
-  for (let i = 0; i < len; i++) {
-    let element = arr[i]
-    let updatedCount = (frequencies.get(element) || 0) + 1
-    frequencies.set(element, updatedCount)
-
-    if (updatedCount > maxOccurrences) {
-      maxOccurrences = updatedCount
-      maxOccurenceCount = 0
-      sum = 0
-    }
-
-    if (updatedCount >= maxOccurrences) {
-      maxOccurenceCount++
-      sum += element
-    }
-  }
-
-  return sum / maxOccurenceCount
-}
-
-class AggregateCollection {
-  constructor() {
-    /** @type number[] */
-    this._items = []
-    this._sum = 0
-  }
-
-  /**
-   * Add a new Integer at the end of this AggregateCollection
-   * @param {number} item - The item to add
-   */
-  push(item) {
-    this._items.push(item)
-    this._sum += item
-  }
-
-  size() {
-    return this._items.length
-  }
-
-  aggregate() {
-    let len = this._items.length
-
-    if (len === 0) {
-      return {
-        min: 0,
-        max: 0,
-        mean: 0,
-        mode: 0,
-        range: 0,
-        sum: 0,
-      }
-    }
-
-    // TODO: can we avoid this sort()? It's slow
-    /** @type Number[] */
-    let sorted = this._items.slice().sort((a, b) => a - b)
-    let min = sorted[0]
-    let max = sorted[len - 1]
-
-    let mode = Mode(sorted)
-    let sum = this._sum
-
-    return {
-      min,
-      max,
-      mean: sum / len,
-      mode,
-      range: max - min,
-      sum: sum,
-    }
-  }
-
-  /**
-   * @returns {number[]} All _items in this collection
-   */
-  toArray() {
-    return this._items
-  }
-}
-
-export {
-  AggregateCollection
-}
\ No newline at end of file
diff --git a/src/aggregate-collection.test.js b/src/aggregate-collection.test.js
deleted file mode 100644
index 3cfdce8e..00000000
--- a/src/aggregate-collection.test.js
+++ /dev/null
@@ -1,45 +0,0 @@
-import { suite } from 'uvu';
-import * as assert from 'uvu/assert';
-import { AggregateCollection } from './aggregate-collection.js'
-
-const CollectionSuite = suite('AggregateCollection')
-
-CollectionSuite('aggregates correctly', () => {
-  const fixture = new AggregateCollection()
-  fixture.push(1)
-  fixture.push(2)
-  fixture.push(25)
-  fixture.push(3)
-  fixture.push(4)
-  fixture.push(4)
-  const actual = fixture.aggregate()
-  const expected = {
-    max: 25,
-    min: 1,
-    range: 24,
-    mean: 39 / 6,
-    mode: 4,
-    sum: 39,
-  }
-
-  assert.equal(actual, expected)
-  assert.equal(fixture.toArray(), [1, 2, 25, 3, 4, 4])
-})
-
-CollectionSuite('handles collections without values', () => {
-  const fixture = new AggregateCollection()
-  const aggregate = fixture.aggregate()
-  const items = fixture.toArray()
-
-  assert.equal(aggregate, {
-    max: 0,
-    min: 0,
-    range: 0,
-    mean: 0,
-    mode: 0,
-    sum: 0,
-  })
-  assert.equal(items, [])
-})
-
-CollectionSuite.run()
\ No newline at end of file
diff --git a/src/aggregate-collection.test.ts b/src/aggregate-collection.test.ts
new file mode 100644
index 00000000..cedc8da5
--- /dev/null
+++ b/src/aggregate-collection.test.ts
@@ -0,0 +1,40 @@
+import { test, expect } from 'vitest'
+import { AggregateCollection } from './aggregate-collection.js'
+
+test('aggregates correctly', () => {
+	const fixture = new AggregateCollection()
+	fixture.push(1)
+	fixture.push(2)
+	fixture.push(25)
+	fixture.push(3)
+	fixture.push(4)
+	fixture.push(4)
+	const actual = fixture.aggregate()
+	const expected = {
+		max: 25,
+		min: 1,
+		range: 24,
+		mean: 39 / 6,
+		mode: 4,
+		sum: 39,
+	}
+
+	expect(actual).toEqual(expected)
+	expect(fixture.toArray()).toEqual([1, 2, 25, 3, 4, 4])
+})
+
+test('handles collections without values', () => {
+	const fixture = new AggregateCollection()
+	const aggregate = fixture.aggregate()
+	const items = fixture.toArray()
+
+	expect(aggregate).toEqual({
+		max: 0,
+		min: 0,
+		range: 0,
+		mean: 0,
+		mode: 0,
+		sum: 0,
+	})
+	expect(items).toEqual([])
+})
diff --git a/src/aggregate-collection.ts b/src/aggregate-collection.ts
new file mode 100644
index 00000000..be303a03
--- /dev/null
+++ b/src/aggregate-collection.ts
@@ -0,0 +1,94 @@
+/**
+ * Find the mode (most occurring value) in an array of Numbers
+ * Takes the mean/average of multiple values if multiple values occur the same amount of times.
+ *
+ * @see https://github.com/angus-c/just/blob/684af9ca0c7808bc78543ec89379b1fdfce502b1/packages/array-mode/index.js
+ * @param arr - Array to find the mode value for
+ * @returns mode - The `mode` value of `arr`
+ */
+function Mode(arr: unknown[]): number {
+	let frequencies = new Map()
+	let maxOccurrences = -1
+	let maxOccurenceCount = 0
+	let sum = 0
+	let len = arr.length
+
+	for (let i = 0; i < len; i++) {
+		let element = arr[i]
+		let updatedCount = (frequencies.get(element) || 0) + 1
+		frequencies.set(element, updatedCount)
+
+		if (updatedCount > maxOccurrences) {
+			maxOccurrences = updatedCount
+			maxOccurenceCount = 0
+			sum = 0
+		}
+
+		if (updatedCount >= maxOccurrences) {
+			maxOccurenceCount++
+			// @ts-expect-error TODO: fix this
+			sum += element
+		}
+	}
+
+	return sum / maxOccurenceCount
+}
+
+export class AggregateCollection {
+	#items: number[]
+	#sum: number
+
+	constructor() {
+		this.#items = []
+		this.#sum = 0
+	}
+
+	/**
+	 * Add a new Integer at the end of this AggregateCollection
+	 * @param item - The item to add
+	 */
+	push(item: number) {
+		this.#items.push(item)
+		this.#sum += item
+	}
+
+	size() {
+		return this.#items.length
+	}
+
+	aggregate() {
+		let len = this.#items.length
+
+		if (len === 0) {
+			return {
+				min: 0,
+				max: 0,
+				mean: 0,
+				mode: 0,
+				range: 0,
+				sum: 0,
+			}
+		}
+
+		// TODO: can we avoid this sort()? It's slow
+		let sorted = this.#items.slice().sort((a, b) => a - b)
+		let min = sorted[0]!
+		let max = sorted[len - 1]!
+
+		let mode = Mode(sorted)
+		let sum = this.#sum
+
+		return {
+			min,
+			max,
+			mean: sum / len,
+			mode,
+			range: max - min,
+			sum: sum,
+		}
+	}
+
+	toArray() {
+		return this.#items
+	}
+}
diff --git a/src/atrules/atrules.js b/src/atrules/atrules.js
deleted file mode 100644
index 45d0e876..00000000
--- a/src/atrules/atrules.js
+++ /dev/null
@@ -1,94 +0,0 @@
-import { strEquals, startsWith, endsWith } from '../string-utils.js'
-import walk from 'css-tree/walker'
-import {
-  Identifier,
-  MediaQuery,
-  Declaration,
-} from '../css-tree-node-types.js'
-
-/**
- * Check whether node.property === property and node.value === value,
- * but case-insensitive and fast.
- * @param {import('css-tree').Declaration} node
- * @param {string} property - The CSS property to compare with (case-insensitive)
- * @param {string} value - The identifier/keyword value to compare with
- * @returns true if declaratioNode is the given property: value, false otherwise
- */
-function isPropertyValue(node, property, value) {
-  let firstChild = node.value.children.first
-  return strEquals(property, node.property)
-    && firstChild.type === Identifier
-    && strEquals(value, firstChild.name)
-}
-
-/**
- * Check if an @supports atRule is a browserhack
- * @param {import('css-tree').AtrulePrelude} prelude
- * @returns true if the atrule is a browserhack
- */
-export function isSupportsBrowserhack(prelude) {
-  let returnValue = false
-
-  walk(prelude, function (node) {
-    if (node.type === Declaration) {
-      if (
-        isPropertyValue(node, '-webkit-appearance', 'none')
-        || isPropertyValue(node, '-moz-appearance', 'meterbar')
-      ) {
-        returnValue = true
-        return this.break
-      }
-    }
-  })
-
-  return returnValue
-}
-
-/**
- * Check if a @media atRule is a browserhack
- * @param {import('css-tree').AtrulePrelude} prelude
- * @returns true if the atrule is a browserhack
- */
-export function isMediaBrowserhack(prelude) {
-  let returnValue = false
-
-  walk(prelude, function (node) {
-    let name = node.name
-    let value = node.value
-
-    if (node.type === MediaQuery && node.mediaType !== null) {
-      // Note: CSSTree adds a trailing space to \\9
-      if (startsWith('\\0', node.mediaType) || endsWith('\\9 ', node.mediaType)) {
-        returnValue = true
-        return this.break
-      }
-    } else if (node.type === 'Feature' && node.kind === 'media') {
-      if (value && value.unit && value.unit === '\\0') {
-        returnValue = true
-        return this.break
-      }
-      else if (strEquals('-moz-images-in-menus', name)
-        || strEquals('min--moz-device-pixel-ratio', name)
-        || strEquals('-ms-high-contrast', name)
-      ) {
-        returnValue = true
-        return this.break
-      }
-      else if (strEquals('min-resolution', name)
-        && value && strEquals('.001', value.value)
-        && strEquals('dpcm', value.unit)
-      ) {
-        returnValue = true
-        return this.break
-      }
-      else if (strEquals('-webkit-min-device-pixel-ratio', name)) {
-        if (value && value.value && (strEquals('0', value.value) || strEquals('10000', value.value))) {
-          returnValue = true
-          return this.break
-        }
-      }
-    }
-  })
-
-  return returnValue
-}
\ No newline at end of file
diff --git a/src/atrules/atrules.test.js b/src/atrules/atrules.test.js
deleted file mode 100644
index 86e4f5a9..00000000
--- a/src/atrules/atrules.test.js
+++ /dev/null
@@ -1,1003 +0,0 @@
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
-import { analyze } from '../index.js'
-
-const AtRules = suite('at-rules')
-
-AtRules('counts total atrules', () => {
-  let css = `
-    @import url(test.css);
-
-    @layer a, b, c;
-
-    @media all {
-      a {}
-    }
-
-    @supports (display: grid) {
-      a {}
-    }
-  `
-  let actual = analyze(css).atrules
-  assert.is(actual.total, 4)
-  assert.is(actual.totalUnique, 4)
-  assert.equal(actual.unique, {
-    'import': 1,
-    'layer': 1,
-    'media': 1,
-    'supports': 1,
-  })
-  assert.equal(actual.uniquenessRatio, 4 / 4)
-})
-
-AtRules('calculates complexity', () => {
-  let css = `
-    /* 1 */
-    @import url(test.css);
-
-    /* 1 */
-    @layer a, b, c;
-    /* 2 */
-    @layer {}
-
-    /* 1 */
-    @supports (display: grid) {}
-    /* 2 */
-    @supports (-webkit-appearance: none) {}
-
-    /* 1 */
-    @media all {}
-    /* 2 */
-    @media (min-resolution: .001dpcm) {}
-
-    /* 1 */
-    @font-face {
-      font-family: Arial;
-    }
-
-    /* 1 */
-    @keyframes one {}
-    /* 2 */
-    @-webkit-keyframes one {}
-  `
-  let actual = analyze(css).atrules.complexity
-  assert.equal(actual, {
-    min: 1,
-    max: 2,
-    mean: 14 / 10,
-    mode: 1,
-    range: 1,
-    sum: 14,
-  })
-})
-
-AtRules('finds @layer', () => {
-  // Fixture is pretty much a straight copy from all code examples from
-  // https://css-tricks.com/css-cascade-layers/
-  const fixture = `
-    @import url('test.css') layer;
-    @import url('test.css') layer();
-    @import url('test.css') layer(test);
-    @import url('test.css') layer(test.abc);
-
-    /* establish a layer order up-front, from lowest to highest priority */
-    @layer reset, defaults, patterns, components, utilities, overrides;
-
-    /* add styles to layers */
-    @layer utilities {
-      /* high layer priority, despite low specificity */
-      [data-color='brand'] {
-        color: var(--brand, rebeccapurple);
-      }
-    }
-
-    @layer defaults {
-      /* higher specificity, but lower layer priority */
-      a:any-link { color: maroon; }
-    }
-
-    /* un-layered styles have the highest priority */
-    a {
-      color: mediumvioletred;
-    }
-
-    @layer layer-1 { a { color: red; } }
-    @layer layer-2 { a { color: orange; } }
-    @layer layer-3 {
-      @layer sub-layer-1 { a { color: yellow; } }
-      @layer sub-layer-2 { a { color: green; } }
-      /* un-nested */ a { color: blue; }
-      @layer {
-        anonymous {}
-      }
-    }
-    /* un-layered */ a { color: indigo; }
-
-    @layer reset, defaults, framework;
-    @layer components, defaults, framework, reset, utilities;
-
-    @layer one {
-      /* sorting the sub-layers */
-      @layer two, three;
-
-      /* styles ... */
-      @layer three { /* styles ... */ }
-      @layer two { /* styles ... */ }
-    }
-
-    /* sorting nested layers directly */
-    @layer one.two, one.three;
-
-    /* adding to nested layers directly */
-    @layer one.three { /* ... */ }
-    @layer one.two { /* ... */ }
-
-    @layer reset.type, default.type, reset.media, default.media;
-
-    @layer
-      reset,
-      default,
-      themes,
-      patterns,
-      layouts,
-      components,
-      utilities;
-
-    @layer components {
-      @layer defaults, structures, themes, utilities;
-    }
-
-    /* Anonymous layer (no prelude/layer name) */
-    @layer {
-      test {
-        color: green;
-      }
-    }
-  `
-  const actual = analyze(fixture).atrules.layer
-  const expected = {
-    total: 50,
-    totalUnique: 28,
-    unique: {
-      "test": 1,
-      "test.abc": 1,
-      "defaults": 5,
-      "layer-1": 1,
-      "layer-2": 1,
-      "layer-3": 1,
-      "sub-layer-1": 1,
-      "sub-layer-2": 1,
-      "reset": 4,
-      "framework": 2,
-      "components": 4,
-      "utilities": 5,
-      "one": 1,
-      "two": 2,
-      "three": 2,
-      "one.two": 2,
-      "one.three": 2,
-      "reset.type": 1,
-      "default.type": 1,
-      "reset.media": 1,
-      "default.media": 1,
-      "default": 1,
-      "themes": 2,
-      "patterns": 2,
-      "layouts": 1,
-      "structures": 1,
-      "overrides": 1,
-      "<anonymous>": 2,
-    },
-    uniquenessRatio: 28 / 50
-  }
-
-  assert.equal(actual, expected)
-})
-
-AtRules('finds @font-face', () => {
-  const fixture = `
-    @font-face {
-      font-family: Arial;
-      src: url("https://url-to-arial.woff");
-    }
-
-    @font-face {
-      font-display: swap;
-      font-family: Test;
-      font-stretch: condensed;
-      font-style: italic;
-      font-weight: 700;
-      font-variant: no-common-ligatures proportional-nums;
-      font-feature-settings: "liga" 0;
-      font-variation-settings: "xhgt" 0.7;
-      src: local("Input Mono");
-      unicode-range: U+0025-00FF;
-    }
-
-    @font-face {
-      font-family: 'Input Mono';
-      src: local('Input Mono') url("https://url-to-input-mono.woff");
-    }
-
-    @font-face {
-      font-family: MyHelvetica;
-      src: local("Helvetica Neue Bold"), local("HelveticaNeue-Bold"), url(MgOpenModernaBold.ttf);
-      font-weight: bold;
-    }
-
-    /* Duplicate @font-face in Media Query */
-    @media (min-width: 1000px) {
-      @font-face {
-        font-family: 'Input Mono';
-        src: local('Input Mono') url("https://url-to-input-mono.woff");
-      }
-    }`
-  const actual = analyze(fixture).atrules.fontface
-  const expected = {
-    total: 5,
-    totalUnique: 5,
-    unique: [
-      {
-        "font-family": "Arial",
-        "src": "url(\"https://url-to-arial.woff\")"
-      },
-      {
-        "font-display": `swap`,
-        "font-family": `Test`,
-        "font-stretch": `condensed`,
-        "font-style": `italic`,
-        "font-weight": `700`,
-        "font-variant": `no-common-ligatures proportional-nums`,
-        "font-feature-settings": `"liga" 0`,
-        "font-variation-settings": `"xhgt" 0.7`,
-        "src": `local("Input Mono")`,
-        "unicode-range": `U+0025-00FF`,
-      },
-      {
-        "font-family": "'Input Mono'",
-        "src": "local('Input Mono') url(\"https://url-to-input-mono.woff\")"
-      },
-      {
-        'font-family': 'MyHelvetica',
-        'src': 'local("Helvetica Neue Bold"), local("HelveticaNeue-Bold"), url(MgOpenModernaBold.ttf)',
-        'font-weight': 'bold',
-      },
-      {
-        "font-family": "'Input Mono'",
-        "src": "local('Input Mono') url(\"https://url-to-input-mono.woff\")"
-      }
-    ],
-    uniquenessRatio: 1
-  }
-
-  assert.equal(actual, expected)
-})
-
-AtRules('finds @font-face', () => {
-  const fixture = `
-    @font-face {
-      font-family: Arial;
-      src: url("https://url-to-arial.woff");
-    }
-
-    @font-face {
-      font-display: swap;
-      font-family: Test;
-      font-stretch: condensed;
-      font-style: italic;
-      font-weight: 700;
-      font-variant: no-common-ligatures proportional-nums;
-      font-feature-settings: "liga" 0;
-      font-variation-settings: "xhgt" 0.7;
-      src: local("Input Mono");
-      unicode-range: U+0025-00FF;
-    }
-
-    @font-face {
-      font-family: 'Input Mono';
-      src: local('Input Mono') url("https://url-to-input-mono.woff");
-    }
-
-    @font-face {
-      font-family: MyHelvetica;
-      src: local("Helvetica Neue Bold"), local("HelveticaNeue-Bold"), url(MgOpenModernaBold.ttf);
-      font-weight: bold;
-    }
-
-    /* Duplicate @font-face in Media Query */
-    @media (min-width: 1000px) {
-      @font-face {
-        font-family: 'Input Mono';
-        src: local('Input Mono') url("https://url-to-input-mono.woff");
-      }
-    }`
-  const actual = analyze(fixture, {
-    useLocations: true
-  }).atrules.fontface.uniqueWithLocations
-  const expected = {
-    5: [{
-      line: 2,
-      column: 5,
-      offset: 5,
-      length: 89,
-    }],
-    100: [{
-      line: 7,
-      column: 5,
-      offset: 100,
-      length: 357,
-    }],
-    463: [{
-      line: 20,
-      column: 5,
-      offset: 463,
-      length: 121,
-    }],
-    590: [{
-      line: 25,
-      column: 5,
-      offset: 590,
-      length: 173,
-    }],
-    850: [{
-      line: 33,
-      column: 7,
-      offset: 850,
-      length: 127,
-    }],
-  }
-
-  assert.equal(actual, expected)
-})
-
-AtRules('handles @font-face encoding issues (GH-307)', () => {
-  // Actual CSS once found in a <style> tag on vistaprint.nl
-  // CSSTree parses it without errors, but analyzer failed on it;
-  let css = `
-    @font-face {
-      font-family: &#x27;Graphik&#x27;;
-      font-stretch: normal;
-      font-style: normal;
-      font-weight: 400;
-      font-display: swap;
-      src: url(&#x27;https://www.vistaprint.nl/swan/v1/fonts/graphic_regular2.7c96db81b23a97fd67cbeb7e7efad583.woff2&#x27;) format(&#x27;woff2&#x27;),
-        url(&#x27;https://www.vistaprint.nl/swan/v1/fonts/graphic_regular.e694f50e9c3a4ee999da756a90b0e872.woff&#x27;) format(&#x27;woff&#x27;);
-    }
-
-    @font-face {
-      font-family: &#x27;Graphik&#x27;;
-      font-stretch: normal;
-      font-style: normal;
-      font-weight: 700;
-      font-display: swap;
-      src: url(&#x27;https://www.vistaprint.nl/swan/v1/fonts/graphic_medium2.3829398551b96ac319a48122465462c2.woff2&#x27;) format(&#x27;woff2&#x27;),
-        url(&#x27;https://www.vistaprint.nl/swan/v1/fonts/graphic_medium.1e5761591bb4bdd7e1d6ef96bb7cef90.woff&#x27;) format(&#x27;woff&#x27;);
-    }
-  `
-  assert.not.throws(() => analyze(css))
-
-  let actual = analyze(css).atrules.fontface
-  assert.is(actual.total, 2)
-  assert.equal(actual.unique[0], {
-    'font-family': `&#x27`,
-    'font-stretch': `normal`,
-    'font-style': `normal`,
-    'font-weight': `400`,
-    'font-display': `swap`,
-    'src': `url(&#x27;https://www.vistaprint.nl/swan/v1/fonts/graphic_regular2.7c96db81b23a97fd67cbeb7e7efad583.woff2&#x27;) format(&#x27;woff2&#x27;),
-        url(&#x27;https://www.vistaprint.nl/swan/v1/fonts/graphic_regular.e694f50e9c3a4ee999da756a90b0e872.woff&#x27;) format(&#x27;woff&#x27;)`
-  })
-})
-
-AtRules('finds @imports', () => {
-  const fixture = `
-    @import "https://example.com/without-url";
-    @import url("https://example.com/with-url");
-    @import url("https://example.com/with-media-query") screen and (min-width: 33em);
-    @import url("https://example.com/with-multiple-media-queries") screen, projection;
-
-    /* styles imported into to the <layer-name> layer */
-    @import url('example.css') layer(named-layer);
-
-    /* styles imported into to a new anonymous layer */
-    @import url('../example.css') layer;
-
-    @import url('remedy.css') layer(reset.remedy);
-
-    @import 'test.css' supports((display: grid));
-    @import 'test.css' supports(not (display: grid));
-    @import 'test.css' supports(selector(a:has(b)));
-    /*@import "test.css" supports((selector(h2 > p) and (font-tech(color-COLRv1))));*/
-
-    /* @import without prelude */
-    @import;
-  `
-  const actual = analyze(fixture).atrules
-  const expected = {
-    total: 10,
-    totalUnique: 10,
-    unique: {
-      '"https://example.com/without-url"': 1,
-      'url("https://example.com/with-url")': 1,
-      'url("https://example.com/with-media-query") screen and (min-width: 33em)': 1,
-      'url("https://example.com/with-multiple-media-queries") screen, projection': 1,
-      'url(\'example.css\') layer(named-layer)': 1,
-      'url(\'../example.css\') layer': 1,
-      "url('remedy.css') layer(reset.remedy)": 1,
-      "'test.css' supports((display: grid))": 1,
-      "'test.css' supports(not (display: grid))": 1,
-      "'test.css' supports(selector(a:has(b)))": 1,
-    },
-    uniquenessRatio: 1,
-  }
-
-  assert.equal(actual.import, expected)
-
-  const expected_supports = {
-    total: 3,
-    totalUnique: 3,
-    unique: {
-      "(display: grid)": 1,
-      "not (display: grid)": 1,
-      "selector(a:has(b))": 1,
-    },
-    uniquenessRatio: 1,
-    browserhacks: {
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-    },
-  }
-  assert.equal(actual.supports, expected_supports)
-
-  const expected_layers = {
-    total: 2,
-    totalUnique: 2,
-    unique: {
-      "named-layer": 1,
-      'reset.remedy': 1,
-    },
-    uniquenessRatio: 1,
-  }
-  assert.equal(actual.layer, expected_layers)
-})
-
-AtRules('finds @charsets', () => {
-  const fixture = `
-    @charset "UTF-8";
-    @charset "UTF-16";
-
-    /* No prelude */
-    @charset;
-  `
-  const actual = analyze(fixture).atrules.charset
-  const expected = {
-    total: 2,
-    totalUnique: 2,
-    unique: {
-      '"UTF-8"': 1,
-      '"UTF-16"': 1,
-    },
-    uniquenessRatio: 2 / 2
-  }
-
-  assert.equal(actual, expected)
-})
-
-AtRules('finds @supports', () => {
-  const fixture = `
-    @supports (filter: blur(5px)) {}
-    @supports (display: table-cell) and (display: list-item) {}
-    @supports (-webkit-appearance: none) {}
-
-    @media (min-width: 0) {
-      @supports (-webkit-appearance: none) {}
-    }
-
-    /* No prelude */
-    @supports {}
-  `
-  const actual = analyze(fixture).atrules.supports
-
-  assert.equal(actual.total, 4)
-  assert.equal(actual.totalUnique, 3)
-  assert.equal(actual.uniquenessRatio, 3 / 4)
-  assert.equal(actual.unique, {
-    '(filter: blur(5px))': 1,
-    '(display: table-cell) and (display: list-item)': 1,
-    '(-webkit-appearance: none)': 2,
-  })
-})
-
-AtRules('finds @supports browserhacks', () => {
-  const fixture = `
-    @supports (-webkit-appearance:none) {}
-    @supports (-webkit-appearance: none) {}
-    @supports (-moz-appearance:meterbar) {}
-    @supports (-moz-appearance:meterbar) and (display:flex) {}
-    @supports (-moz-appearance:meterbar) and (cursor:zoom-in) {}
-    @supports (-moz-appearance:meterbar) and (background-attachment:local) {}
-    @supports (-moz-appearance:meterbar) and (image-orientation:90deg) {}
-    @supports (-moz-appearance:meterbar) and (all:initial) {}
-    @supports (-moz-appearance:meterbar) and (list-style-type:japanese-formal) {}
-    @supports (-moz-appearance:meterbar) and (background-blend-mode:difference,normal) {}
-
-    /* Not a hack */
-    @supports (color: red) {}
-  `
-  const result = analyze(fixture)
-  const actual = result.atrules.supports.browserhacks
-  const expected = {
-    total: 10,
-    totalUnique: 10,
-    uniquenessRatio: 10 / 10,
-    unique: {
-      '(-webkit-appearance:none)': 1,
-      '(-webkit-appearance: none)': 1,
-      '(-moz-appearance:meterbar)': 1,
-      '(-moz-appearance:meterbar) and (display:flex)': 1,
-      '(-moz-appearance:meterbar) and (cursor:zoom-in)': 1,
-      '(-moz-appearance:meterbar) and (background-attachment:local)': 1,
-      '(-moz-appearance:meterbar) and (image-orientation:90deg)': 1,
-      '(-moz-appearance:meterbar) and (all:initial)': 1,
-      '(-moz-appearance:meterbar) and (list-style-type:japanese-formal)': 1,
-      '(-moz-appearance:meterbar) and (background-blend-mode:difference,normal)': 1,
-    }
-  }
-
-  assert.equal(actual, expected)
-})
-
-AtRules('finds @media', () => {
-  const fixture = `
-    @media screen {}
-    @media screen and (min-width: 33em) {}
-    @media (min-width: 20px) {}
-    @media (max-width: 200px) {}
-    @media screen or print {}
-    @media all and (transform-3d), (-webkit-transform-3d) {}
-
-    @supports (-webkit-appearance: none) {
-      @media (min-width: 0) {}
-    }
-
-    /* No prelude */
-    @media {}
-  `
-  const actual = analyze(fixture).atrules.media
-
-  assert.is(actual.total, 7)
-  assert.is(actual.totalUnique, 7)
-  assert.equal(actual.unique, {
-    'screen': 1,
-    'screen and (min-width: 33em)': 1,
-    '(min-width: 20px)': 1,
-    '(max-width: 200px)': 1,
-    'screen or print': 1,
-    'all and (transform-3d), (-webkit-transform-3d)': 1,
-    '(min-width: 0)': 1,
-  })
-  assert.is(actual.uniquenessRatio, 1)
-})
-
-AtRules('finds @media browserhacks', () => {
-  const fixture = `
-    @media \\0 all {}
-    @media \\0 screen {}
-    @media \\0screen {}
-    @media screen\\9 {}
-    @media \\0screen\\,screen\\9 {}
-    @media screen and (min-width:0\\0) {}
-    @media all and (-moz-images-in-menus:0) and (min-resolution: .001dpcm) {}
-    @media all and (-moz-images-in-menus:0) { @media (min-width: 0px) {} }
-    @media screen and (-moz-images-in-menus:0) {}
-    @media screen and (min--moz-device-pixel-ratio:0) {}
-    @media all and (min--moz-device-pixel-ratio:0) and (min-resolution: .001dpcm) {}
-    @media all and (min--moz-device-pixel-ratio:0) { @media (min-width: 0px) {} }
-    @media all and (min--moz-device-pixel-ratio:0) and (min-resolution: 3e1dpcm) {}
-    @media screen and (-ms-high-contrast: active), (-ms-high-contrast: none) {}
-    @media (min-resolution: .001dpcm) { _:-o-prefocus, .selector {} }
-    @media all and (-webkit-min-device-pixel-ratio:0) and (min-resolution: .001dpcm) { .selector {} }
-    @media all and (-webkit-min-device-pixel-ratio:10000), not all and (-webkit-min-device-pixel-ratio:0) {}
-  `
-
-  const result = analyze(fixture)
-  const actual = result.atrules.media.browserhacks
-  const expected = {
-    total: 17,
-    totalUnique: 17,
-    uniquenessRatio: 1,
-    unique: {
-      "\\0 all": 1,
-      "\\0 screen": 1,
-      "\\0screen": 1,
-      "screen\\9": 1,
-      "\\0screen\\,screen\\9": 1,
-      "screen and (min-width:0\\0)": 1,
-      "all and (-moz-images-in-menus:0) and (min-resolution: .001dpcm)": 1,
-      "all and (-moz-images-in-menus:0)": 1,
-      "screen and (-moz-images-in-menus:0)": 1,
-      "screen and (min--moz-device-pixel-ratio:0)": 1,
-      "all and (min--moz-device-pixel-ratio:0)": 1,
-      "all and (min--moz-device-pixel-ratio:0) and (min-resolution: .001dpcm)": 1,
-      "all and (min--moz-device-pixel-ratio:0) and (min-resolution: 3e1dpcm)": 1,
-      "screen and (-ms-high-contrast: active), (-ms-high-contrast: none)": 1,
-      "(min-resolution: .001dpcm)": 1,
-      "all and (-webkit-min-device-pixel-ratio:0) and (min-resolution: .001dpcm)": 1,
-      "all and (-webkit-min-device-pixel-ratio:10000), not all and (-webkit-min-device-pixel-ratio:0)": 1,
-    }
-  }
-
-  assert.equal(actual, expected)
-})
-
-AtRules('finds Media Features', () => {
-  const fixture = `
-    @media (min-width: 0) {}
-    @media (max-width: 0) {}
-    @media (hover) {}
-    @media (forced-colors: none) {}
-    @media (prefers-color-scheme: dark) {}
-    @media (prefers-reduced-motion: reduce) {}
-    @media (prefers-contrast: more) {}
-
-    @media screen and (50px <= width <= 100px), (min-height: 100px) {}
-    `
-  const actual = analyze(fixture).atrules.media.features
-  const expected = {
-    total: 8,
-    totalUnique: 8,
-    unique: {
-      'min-width': 1,
-      'max-width': 1,
-      'hover': 1,
-      'forced-colors': 1,
-      'prefers-color-scheme': 1,
-      'prefers-reduced-motion': 1,
-      'prefers-contrast': 1,
-      'min-height': 1,
-    },
-    uniquenessRatio: 8 / 8,
-  }
-
-  assert.equal(actual, expected)
-})
-
-AtRules('does not crash on incomplete @media queries', () => {
-  let css = `
-    @media (min-width) {}
-    @media (-moz-images-in-menus) {}
-    @media (min--moz-device-pixel-ratio) {}
-    @media (-ms-high-contrast), (-ms-high-contrast) {}
-    @media (min-resolution) {}
-    @media (-webkit-min-device-pixel-ratio) {}
-  `
-
-  assert.not.throws(() => analyze(css))
-})
-
-AtRules('analyzes @keyframes', () => {
-  const fixture = `
-    @keyframes one {}
-    @keyframes one {}
-    @keyframes TWO {}
-
-    /* No prelude */
-    @keyframes {}
-
-    /* Prefixes */
-    @-webkit-keyframes animation {}
-    @-moz-keyframes animation {}
-    @-o-keyframes animation {}
-  `
-  const actual = analyze(fixture).atrules.keyframes
-  const expected = {
-    total: 6,
-    totalUnique: 5,
-    unique: {
-      '@keyframes one': 2,
-      '@keyframes TWO': 1,
-      '@-webkit-keyframes animation': 1,
-      '@-moz-keyframes animation': 1,
-      '@-o-keyframes animation': 1,
-    },
-    uniquenessRatio: 5 / 6,
-    prefixed: {
-      total: 3,
-      totalUnique: 3,
-      unique: {
-        '@-webkit-keyframes animation': 1,
-        '@-moz-keyframes animation': 1,
-        '@-o-keyframes animation': 1,
-      },
-      uniquenessRatio: 3 / 3,
-      ratio: 3 / 6
-    }
-  }
-
-  assert.equal(actual, expected)
-})
-
-AtRules('counts ratio correctly when no @keyframes present', () => {
-  const fixture = `@media (min-width: 0px) {}`
-  const actual = analyze(fixture)
-  const expected = {
-    total: 0,
-    totalUnique: 0,
-    unique: {},
-    uniquenessRatio: 0,
-    prefixed: {
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-      ratio: 0,
-    },
-  }
-  assert.equal(actual.atrules.keyframes, expected)
-})
-
-AtRules('analyzes container queries', () => {
-  // Fixture contains examples from the spec.
-  // https://drafts.csswg.org/css-contain-3/
-  const fixture = `
-    /* Example 2 */
-    @container (inline-size > 45em) {
-      .media-object {
-        grid-template: 'img content' auto / auto 1fr;
-      }
-    }
-
-    /* Example 3 */
-    @container (width > 40em) {
-      h2 { font-size: 1.5em; }
-    }
-
-    /* Example 4 */
-    @container (--cards) {
-      article {
-        border: thin solid silver;
-        border-radius: 0.5em;
-        padding: 1em;
-      }
-    }
-
-    /* Example 5 */
-    @container page-layout (block-size > 12em) {
-      .card { margin-block: 2em; }
-    }
-
-    @container component-library (inline-size > 30em) {
-      .card { margin-inline: 2em; }
-    }
-
-    /* Example 8 */
-    @container card (inline-size > 30em) and (--responsive = true) {
-      /* styles */
-    }
-
-    /* Example 11 */
-    @container type(inline-size) {
-      /* only applies when an inline-size container is available */
-      h2 { font-size: calc(1.2em + 1cqi); }
-    }
-
-    /* No prelude */
-    @container {}
-  `
-  const result = analyze(fixture)
-  const actual = result.atrules.container
-  const expected = {
-    total: 7,
-    totalUnique: 7,
-    unique: {
-      '(inline-size > 45em)': 1,
-      '(width > 40em)': 1,
-      '(--cards)': 1,
-      'page-layout (block-size > 12em)': 1,
-      'component-library (inline-size > 30em)': 1,
-      'card (inline-size > 30em) and (--responsive = true)': 1,
-      'type(inline-size)': 1,
-    },
-    uniquenessRatio: 7 / 7,
-    names: {
-      total: 3,
-      totalUnique: 3,
-      unique: {
-        'card': 1,
-        'page-layout': 1,
-        'component-library': 1,
-      },
-      uniquenessRatio: 1 / 1,
-    },
-  }
-
-  assert.equal(actual, expected)
-})
-
-AtRules('finds named containers in @container', () => {
-  const fixture = `
-    @container test1 (inline-size > 30em) {}
-    @container test2 (inline-size > 30em) and style(--responsive: true) {}
-    @container style(--responsive: true) {}
-  `
-  const actual = analyze(fixture).atrules.container.names
-  const TOTAL = 2
-  const UNIQUE = 2
-  const expected = {
-    total: TOTAL,
-    totalUnique: TOTAL,
-    unique: {
-      'test1': 1,
-      'test2': 1,
-    },
-    uniquenessRatio: UNIQUE / TOTAL,
-  }
-
-  assert.equal(actual, expected)
-})
-
-AtRules('finds named containers in the `container-name` property', () => {
-  const fixture = `
-    a {
-      container-name: my-layout;
-      container-name: my-component;
-    }
-  `
-  const actual = analyze(fixture).atrules.container.names
-  const TOTAL = 2
-  const UNIQUE = 2
-  const expected = {
-    total: TOTAL,
-    totalUnique: TOTAL,
-    unique: {
-      'my-layout': 1,
-      'my-component': 1,
-    },
-    uniquenessRatio: UNIQUE / TOTAL,
-  }
-
-  assert.equal(actual, expected)
-})
-
-AtRules('finds named containers in the `container` shorthand', () => {
-  const fixture = `
-    a {
-      container: my-layout / size;
-      container: my-component / inline-size;
-    }
-  `
-  const actual = analyze(fixture).atrules.container.names
-  const TOTAL = 2
-  const UNIQUE = 2
-  const expected = {
-    total: TOTAL,
-    totalUnique: TOTAL,
-    unique: {
-      'my-layout': 1,
-      'my-component': 1,
-    },
-    uniquenessRatio: UNIQUE / TOTAL,
-  }
-
-  assert.equal(actual, expected)
-})
-
-AtRules('analyzes @property', () => {
-  const fixture = `
-    /* Examples from https://nerdy.dev/cant-break-this-design-system */
-    @property --focal-size {
-      syntax: '<length-percentage>';
-      initial-value: 100%;
-      inherits: false;
-    }
-
-    @property --hue {
-      syntax: '<angle>';
-      initial-value: .5turn;
-      inherits: false;
-    }
-
-    @property --surface {
-      syntax: '<color>';
-      initial-value: #333;
-      inherits: true;
-    }
-
-    @property --surface-over {
-      syntax: '<color>';
-      initial-value: #444;
-      inherits: true;
-    }
-
-    @property --surface-under {
-      syntax: '<color>';
-      initial-value: #222;
-      inherits: true;
-    }
-    /* end nerdy.dev examples */
-
-    @media all {
-      @layer test {
-        @property --test-dupe {
-          syntax: '<color>';
-          inherits: false;
-        }
-        @property --test-dupe {
-          syntax: '<color>';
-          inherits: false;
-        }
-      }
-    }
-
-    /* No prelude */
-    @property {}
-  `
-  const actual = analyze(fixture).atrules.property
-  const expected = {
-    total: 7,
-    totalUnique: 6,
-    unique: {
-      '--focal-size': 1,
-      '--hue': 1,
-      '--surface': 1,
-      '--surface-over': 1,
-      '--surface-under': 1,
-      '--test-dupe': 2,
-    },
-    uniquenessRatio: 6 / 7
-  }
-
-  assert.equal(actual, expected)
-})
-
-AtRules('tracks nesting depth', () => {
-  const fixture = `
-    a {
-      color: red;
-    }
-
-    b {
-      color: green;
-
-      &:hover {
-        color: blue;
-      }
-
-      color: deepskyblue;
-
-      @container (width > 400px) {
-        color: rebeccapurple
-      }
-    }
-
-    @media print {
-      @supports (display: grid) {
-        c {
-          color: orange;
-        }
-      }
-    }
-  `
-  const actual = analyze(fixture).atrules.nesting
-  const expected = {
-    min: 0,
-    max: 1,
-    mean: 0.6666666666666666,
-    mode: 1,
-    range: 1,
-    sum: 2,
-    items: [1, 0, 1],
-    total: 3,
-    totalUnique: 2,
-    unique: {
-      0: 1,
-      1: 2,
-    },
-    uniquenessRatio: 2 / 3,
-  }
-  assert.equal(actual, expected)
-})
-
-AtRules.run()
\ No newline at end of file
diff --git a/src/atrules/atrules.test.ts b/src/atrules/atrules.test.ts
new file mode 100644
index 00000000..e03a67d6
--- /dev/null
+++ b/src/atrules/atrules.test.ts
@@ -0,0 +1,1009 @@
+import { test, expect } from 'vitest'
+import { analyze } from '../index.js'
+
+test('counts total atrules', () => {
+	let css = `
+    @import url(test.css);
+
+    @layer a, b, c;
+
+    @media all {
+      a {}
+    }
+
+    @supports (display: grid) {
+      a {}
+    }
+  `
+	let actual = analyze(css).atrules
+	expect(actual.total).toEqual(4)
+	expect(actual.totalUnique).toEqual(4)
+	expect(actual.unique).toEqual({
+		import: 1,
+		layer: 1,
+		media: 1,
+		supports: 1,
+	})
+	expect(actual.uniquenessRatio).toEqual(4 / 4)
+})
+
+test('calculates complexity', () => {
+	let css = `
+    /* 1 */
+    @import url(test.css);
+
+    /* 1 */
+    @layer a, b, c;
+    /* 2 */
+    @layer {}
+
+    /* 1 */
+    @supports (display: grid) {}
+    /* 2 */
+    @supports (-webkit-appearance: none) {}
+
+    /* 1 */
+    @media all {}
+    /* 2 */
+    @media (min-resolution: .001dpcm) {}
+
+    /* 1 */
+    @font-face {
+      font-family: Arial;
+    }
+
+    /* 1 */
+    @keyframes one {}
+    /* 2 */
+    @-webkit-keyframes one {}
+  `
+	let actual = analyze(css).atrules.complexity
+	expect(actual).toEqual({
+		min: 1,
+		max: 2,
+		mean: 14 / 10,
+		mode: 1,
+		range: 1,
+		sum: 14,
+	})
+})
+
+test('finds @layer', () => {
+	// Fixture is pretty much a straight copy from all code examples from
+	// https://css-tricks.com/css-cascade-layers/
+	const fixture = `
+    @import url('test.css') layer;
+    @import url('test.css') layer();
+    @import url('test.css') layer(test);
+    @import url('test.css') layer(test.abc);
+
+    /* establish a layer order up-front, from lowest to highest priority */
+    @layer reset, defaults, patterns, components, utilities, overrides;
+
+    /* add styles to layers */
+    @layer utilities {
+      /* high layer priority, despite low specificity */
+      [data-color='brand'] {
+        color: var(--brand, rebeccapurple);
+      }
+    }
+
+    @layer defaults {
+      /* higher specificity, but lower layer priority */
+      a:any-link { color: maroon; }
+    }
+
+    /* un-layered styles have the highest priority */
+    a {
+      color: mediumvioletred;
+    }
+
+    @layer layer-1 { a { color: red; } }
+    @layer layer-2 { a { color: orange; } }
+    @layer layer-3 {
+      @layer sub-layer-1 { a { color: yellow; } }
+      @layer sub-layer-2 { a { color: green; } }
+      /* un-nested */ a { color: blue; }
+      @layer {
+        anonymous {}
+      }
+    }
+    /* un-layered */ a { color: indigo; }
+
+    @layer reset, defaults, framework;
+    @layer components, defaults, framework, reset, utilities;
+
+    @layer one {
+      /* sorting the sub-layers */
+      @layer two, three;
+
+      /* styles ... */
+      @layer three { /* styles ... */ }
+      @layer two { /* styles ... */ }
+    }
+
+    /* sorting nested layers directly */
+    @layer one.two, one.three;
+
+    /* adding to nested layers directly */
+    @layer one.three { /* ... */ }
+    @layer one.two { /* ... */ }
+
+    @layer reset.type, default.type, reset.media, default.media;
+
+    @layer
+      reset,
+      default,
+      themes,
+      patterns,
+      layouts,
+      components,
+      utilities;
+
+    @layer components {
+      @layer defaults, structures, themes, utilities;
+    }
+
+    /* Anonymous layer (no prelude/layer name) */
+    @layer {
+      test {
+        color: green;
+      }
+    }
+  `
+	const actual = analyze(fixture).atrules.layer
+	const expected = {
+		total: 50,
+		totalUnique: 28,
+		unique: {
+			test: 1,
+			'test.abc': 1,
+			defaults: 5,
+			'layer-1': 1,
+			'layer-2': 1,
+			'layer-3': 1,
+			'sub-layer-1': 1,
+			'sub-layer-2': 1,
+			reset: 4,
+			framework: 2,
+			components: 4,
+			utilities: 5,
+			one: 1,
+			two: 2,
+			three: 2,
+			'one.two': 2,
+			'one.three': 2,
+			'reset.type': 1,
+			'default.type': 1,
+			'reset.media': 1,
+			'default.media': 1,
+			default: 1,
+			themes: 2,
+			patterns: 2,
+			layouts: 1,
+			structures: 1,
+			overrides: 1,
+			'<anonymous>': 2,
+		},
+		uniquenessRatio: 28 / 50,
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('finds @font-face', () => {
+	const fixture = `
+    @font-face {
+      font-family: Arial;
+      src: url("https://url-to-arial.woff");
+    }
+
+    @font-face {
+      font-display: swap;
+      font-family: Test;
+      font-stretch: condensed;
+      font-style: italic;
+      font-weight: 700;
+      font-variant: no-common-ligatures proportional-nums;
+      font-feature-settings: "liga" 0;
+      font-variation-settings: "xhgt" 0.7;
+      src: local("Input Mono");
+      unicode-range: U+0025-00FF;
+    }
+
+    @font-face {
+      font-family: 'Input Mono';
+      src: local('Input Mono') url("https://url-to-input-mono.woff");
+    }
+
+    @font-face {
+      font-family: MyHelvetica;
+      src: local("Helvetica Neue Bold"), local("HelveticaNeue-Bold"), url(MgOpenModernaBold.ttf);
+      font-weight: bold;
+    }
+
+    /* Duplicate @font-face in Media Query */
+    @media (min-width: 1000px) {
+      @font-face {
+        font-family: 'Input Mono';
+        src: local('Input Mono') url("https://url-to-input-mono.woff");
+      }
+    }`
+	const actual = analyze(fixture).atrules.fontface
+	const expected = {
+		total: 5,
+		totalUnique: 5,
+		unique: [
+			{
+				'font-family': 'Arial',
+				src: 'url("https://url-to-arial.woff")',
+			},
+			{
+				'font-display': `swap`,
+				'font-family': `Test`,
+				'font-stretch': `condensed`,
+				'font-style': `italic`,
+				'font-weight': `700`,
+				'font-variant': `no-common-ligatures proportional-nums`,
+				'font-feature-settings': `"liga" 0`,
+				'font-variation-settings': `"xhgt" 0.7`,
+				src: `local("Input Mono")`,
+				'unicode-range': `U+0025-00FF`,
+			},
+			{
+				'font-family': "'Input Mono'",
+				src: 'local(\'Input Mono\') url("https://url-to-input-mono.woff")',
+			},
+			{
+				'font-family': 'MyHelvetica',
+				src: 'local("Helvetica Neue Bold"), local("HelveticaNeue-Bold"), url(MgOpenModernaBold.ttf)',
+				'font-weight': 'bold',
+			},
+			{
+				'font-family': "'Input Mono'",
+				src: 'local(\'Input Mono\') url("https://url-to-input-mono.woff")',
+			},
+		],
+		uniquenessRatio: 1,
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('finds @font-face', () => {
+	const fixture = `
+    @font-face {
+      font-family: Arial;
+      src: url("https://url-to-arial.woff");
+    }
+
+    @font-face {
+      font-display: swap;
+      font-family: Test;
+      font-stretch: condensed;
+      font-style: italic;
+      font-weight: 700;
+      font-variant: no-common-ligatures proportional-nums;
+      font-feature-settings: "liga" 0;
+      font-variation-settings: "xhgt" 0.7;
+      src: local("Input Mono");
+      unicode-range: U+0025-00FF;
+    }
+
+    @font-face {
+      font-family: 'Input Mono';
+      src: local('Input Mono') url("https://url-to-input-mono.woff");
+    }
+
+    @font-face {
+      font-family: MyHelvetica;
+      src: local("Helvetica Neue Bold"), local("HelveticaNeue-Bold"), url(MgOpenModernaBold.ttf);
+      font-weight: bold;
+    }
+
+    /* Duplicate @font-face in Media Query */
+    @media (min-width: 1000px) {
+      @font-face {
+        font-family: 'Input Mono';
+        src: local('Input Mono') url("https://url-to-input-mono.woff");
+      }
+    }`
+	const actual = analyze(fixture, {
+		useLocations: true,
+	}).atrules.fontface.uniqueWithLocations
+	const expected = {
+		5: [
+			{
+				line: 2,
+				column: 5,
+				offset: 5,
+				length: 89,
+			},
+		],
+		100: [
+			{
+				line: 7,
+				column: 5,
+				offset: 100,
+				length: 357,
+			},
+		],
+		463: [
+			{
+				line: 20,
+				column: 5,
+				offset: 463,
+				length: 121,
+			},
+		],
+		590: [
+			{
+				line: 25,
+				column: 5,
+				offset: 590,
+				length: 173,
+			},
+		],
+		850: [
+			{
+				line: 33,
+				column: 7,
+				offset: 850,
+				length: 127,
+			},
+		],
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('handles @font-face encoding issues (GH-307)', () => {
+	// Actual CSS once found in a <style> tag on vistaprint.nl
+	// CSSTree parses it without errors, but analyzer failed on it;
+	let css = `
+    @font-face {
+      font-family: &#x27;Graphik&#x27;;
+      font-stretch: normal;
+      font-style: normal;
+      font-weight: 400;
+      font-display: swap;
+      src: url(&#x27;https://www.vistaprint.nl/swan/v1/fonts/graphic_regular2.7c96db81b23a97fd67cbeb7e7efad583.woff2&#x27;) format(&#x27;woff2&#x27;),
+        url(&#x27;https://www.vistaprint.nl/swan/v1/fonts/graphic_regular.e694f50e9c3a4ee999da756a90b0e872.woff&#x27;) format(&#x27;woff&#x27;);
+    }
+
+    @font-face {
+      font-family: &#x27;Graphik&#x27;;
+      font-stretch: normal;
+      font-style: normal;
+      font-weight: 700;
+      font-display: swap;
+      src: url(&#x27;https://www.vistaprint.nl/swan/v1/fonts/graphic_medium2.3829398551b96ac319a48122465462c2.woff2&#x27;) format(&#x27;woff2&#x27;),
+        url(&#x27;https://www.vistaprint.nl/swan/v1/fonts/graphic_medium.1e5761591bb4bdd7e1d6ef96bb7cef90.woff&#x27;) format(&#x27;woff&#x27;);
+    }
+  `
+	expect(() => analyze(css)).not.toThrowError()
+
+	let actual = analyze(css).atrules.fontface
+	expect(actual.total).toEqual(2)
+	let expected = {
+		'font-family': `&#x27`,
+		'font-stretch': `normal`,
+		'font-style': `normal`,
+		'font-weight': `400`,
+		'font-display': `swap`,
+		src: `url(&#x27;https://www.vistaprint.nl/swan/v1/fonts/graphic_regular2.7c96db81b23a97fd67cbeb7e7efad583.woff2&#x27;) format(&#x27;woff2&#x27;),
+        url(&#x27;https://www.vistaprint.nl/swan/v1/fonts/graphic_regular.e694f50e9c3a4ee999da756a90b0e872.woff&#x27;) format(&#x27;woff&#x27;)`,
+	}
+	expect(actual.unique[0]).toEqual(expected)
+})
+
+test('finds @imports', () => {
+	const fixture = `
+    @import "https://example.com/without-url";
+    @import url("https://example.com/with-url");
+    @import url("https://example.com/with-media-query") screen and (min-width: 33em);
+    @import url("https://example.com/with-multiple-media-queries") screen, projection;
+
+    /* styles imported into to the <layer-name> layer */
+    @import url('example.css') layer(named-layer);
+
+    /* styles imported into to a new anonymous layer */
+    @import url('../example.css') layer;
+
+    @import url('remedy.css') layer(reset.remedy);
+
+    @import 'test.css' supports((display: grid));
+    @import 'test.css' supports(not (display: grid));
+    @import 'test.css' supports(selector(a:has(b)));
+    /*@import "test.css" supports((selector(h2 > p) and (font-tech(color-COLRv1))));*/
+
+    /* @import without prelude */
+    @import;
+  `
+	const actual = analyze(fixture).atrules
+	const expected = {
+		total: 10,
+		totalUnique: 10,
+		unique: {
+			'"https://example.com/without-url"': 1,
+			'url("https://example.com/with-url")': 1,
+			'url("https://example.com/with-media-query") screen and (min-width: 33em)': 1,
+			'url("https://example.com/with-multiple-media-queries") screen, projection': 1,
+			"url('example.css') layer(named-layer)": 1,
+			"url('../example.css') layer": 1,
+			"url('remedy.css') layer(reset.remedy)": 1,
+			"'test.css' supports((display: grid))": 1,
+			"'test.css' supports(not (display: grid))": 1,
+			"'test.css' supports(selector(a:has(b)))": 1,
+		},
+		uniquenessRatio: 1,
+	}
+
+	expect(actual.import).toEqual(expected)
+
+	const expected_supports = {
+		total: 3,
+		totalUnique: 3,
+		unique: {
+			'(display: grid)': 1,
+			'not (display: grid)': 1,
+			'selector(a:has(b))': 1,
+		},
+		uniquenessRatio: 1,
+		browserhacks: {
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+		},
+	}
+	expect(actual.supports).toEqual(expected_supports)
+
+	const expected_layers = {
+		total: 2,
+		totalUnique: 2,
+		unique: {
+			'named-layer': 1,
+			'reset.remedy': 1,
+		},
+		uniquenessRatio: 1,
+	}
+	expect(actual.layer).toEqual(expected_layers)
+})
+
+test('finds @charsets', () => {
+	const fixture = `
+    @charset "UTF-8";
+    @charset "UTF-16";
+
+    /* No prelude */
+    @charset;
+  `
+	const actual = analyze(fixture).atrules.charset
+	const expected = {
+		total: 2,
+		totalUnique: 2,
+		unique: {
+			'"UTF-8"': 1,
+			'"UTF-16"': 1,
+		},
+		uniquenessRatio: 2 / 2,
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('finds @supports', () => {
+	const fixture = `
+    @supports (filter: blur(5px)) {}
+    @supports (display: table-cell) and (display: list-item) {}
+    @supports (-webkit-appearance: none) {}
+
+    @media (min-width: 0) {
+      @supports (-webkit-appearance: none) {}
+    }
+
+    /* No prelude */
+    @supports {}
+  `
+	const actual = analyze(fixture).atrules.supports
+
+	expect(actual.total).toEqual(4)
+	expect(actual.totalUnique).toEqual(3)
+	expect(actual.uniquenessRatio).toEqual(3 / 4)
+	expect(actual.unique).toEqual({
+		'(filter: blur(5px))': 1,
+		'(display: table-cell) and (display: list-item)': 1,
+		'(-webkit-appearance: none)': 2,
+	})
+})
+
+test('finds @supports browserhacks', () => {
+	const fixture = `
+    @supports (-webkit-appearance:none) {}
+    @supports (-webkit-appearance: none) {}
+    @supports (-moz-appearance:meterbar) {}
+    @supports (-moz-appearance:meterbar) and (display:flex) {}
+    @supports (-moz-appearance:meterbar) and (cursor:zoom-in) {}
+    @supports (-moz-appearance:meterbar) and (background-attachment:local) {}
+    @supports (-moz-appearance:meterbar) and (image-orientation:90deg) {}
+    @supports (-moz-appearance:meterbar) and (all:initial) {}
+    @supports (-moz-appearance:meterbar) and (list-style-type:japanese-formal) {}
+    @supports (-moz-appearance:meterbar) and (background-blend-mode:difference,normal) {}
+
+    /* Not a hack */
+    @supports (color: red) {}
+  `
+	const result = analyze(fixture)
+	const actual = result.atrules.supports.browserhacks
+	const expected = {
+		total: 10,
+		totalUnique: 10,
+		uniquenessRatio: 10 / 10,
+		unique: {
+			'(-webkit-appearance:none)': 1,
+			'(-webkit-appearance: none)': 1,
+			'(-moz-appearance:meterbar)': 1,
+			'(-moz-appearance:meterbar) and (display:flex)': 1,
+			'(-moz-appearance:meterbar) and (cursor:zoom-in)': 1,
+			'(-moz-appearance:meterbar) and (background-attachment:local)': 1,
+			'(-moz-appearance:meterbar) and (image-orientation:90deg)': 1,
+			'(-moz-appearance:meterbar) and (all:initial)': 1,
+			'(-moz-appearance:meterbar) and (list-style-type:japanese-formal)': 1,
+			'(-moz-appearance:meterbar) and (background-blend-mode:difference,normal)': 1,
+		},
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('finds @media', () => {
+	const fixture = `
+    @media screen {}
+    @media screen and (min-width: 33em) {}
+    @media (min-width: 20px) {}
+    @media (max-width: 200px) {}
+    @media screen or print {}
+    @media all and (transform-3d), (-webkit-transform-3d) {}
+
+    @supports (-webkit-appearance: none) {
+      @media (min-width: 0) {}
+    }
+
+    /* No prelude */
+    @media {}
+  `
+	const actual = analyze(fixture).atrules.media
+
+	expect(actual.total).toEqual(7)
+	expect(actual.totalUnique).toEqual(7)
+	expect(actual.unique).toEqual({
+		screen: 1,
+		'screen and (min-width: 33em)': 1,
+		'(min-width: 20px)': 1,
+		'(max-width: 200px)': 1,
+		'screen or print': 1,
+		'all and (transform-3d), (-webkit-transform-3d)': 1,
+		'(min-width: 0)': 1,
+	})
+	expect(actual.uniquenessRatio).toEqual(1)
+})
+
+test('finds @media browserhacks', () => {
+	const fixture = `
+    @media \\0 all {}
+    @media \\0 screen {}
+    @media \\0screen {}
+    @media screen\\9 {}
+    @media \\0screen\\,screen\\9 {}
+    @media screen and (min-width:0\\0) {}
+    @media all and (-moz-images-in-menus:0) and (min-resolution: .001dpcm) {}
+    @media all and (-moz-images-in-menus:0) { @media (min-width: 0px) {} }
+    @media screen and (-moz-images-in-menus:0) {}
+    @media screen and (min--moz-device-pixel-ratio:0) {}
+    @media all and (min--moz-device-pixel-ratio:0) and (min-resolution: .001dpcm) {}
+    @media all and (min--moz-device-pixel-ratio:0) { @media (min-width: 0px) {} }
+    @media all and (min--moz-device-pixel-ratio:0) and (min-resolution: 3e1dpcm) {}
+    @media screen and (-ms-high-contrast: active), (-ms-high-contrast: none) {}
+    @media (min-resolution: .001dpcm) { _:-o-prefocus, .selector {} }
+    @media all and (-webkit-min-device-pixel-ratio:0) and (min-resolution: .001dpcm) { .selector {} }
+    @media all and (-webkit-min-device-pixel-ratio:10000), not all and (-webkit-min-device-pixel-ratio:0) {}
+  `
+
+	const result = analyze(fixture)
+	const actual = result.atrules.media.browserhacks
+	const expected = {
+		total: 17,
+		totalUnique: 17,
+		uniquenessRatio: 1,
+		unique: {
+			'\\0 all': 1,
+			'\\0 screen': 1,
+			'\\0screen': 1,
+			'screen\\9': 1,
+			'\\0screen\\,screen\\9': 1,
+			'screen and (min-width:0\\0)': 1,
+			'all and (-moz-images-in-menus:0) and (min-resolution: .001dpcm)': 1,
+			'all and (-moz-images-in-menus:0)': 1,
+			'screen and (-moz-images-in-menus:0)': 1,
+			'screen and (min--moz-device-pixel-ratio:0)': 1,
+			'all and (min--moz-device-pixel-ratio:0)': 1,
+			'all and (min--moz-device-pixel-ratio:0) and (min-resolution: .001dpcm)': 1,
+			'all and (min--moz-device-pixel-ratio:0) and (min-resolution: 3e1dpcm)': 1,
+			'screen and (-ms-high-contrast: active), (-ms-high-contrast: none)': 1,
+			'(min-resolution: .001dpcm)': 1,
+			'all and (-webkit-min-device-pixel-ratio:0) and (min-resolution: .001dpcm)': 1,
+			'all and (-webkit-min-device-pixel-ratio:10000), not all and (-webkit-min-device-pixel-ratio:0)': 1,
+		},
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('finds Media Features', () => {
+	const fixture = `
+    @media (min-width: 0) {}
+    @media (max-width: 0) {}
+    @media (hover) {}
+    @media (forced-colors: none) {}
+    @media (prefers-color-scheme: dark) {}
+    @media (prefers-reduced-motion: reduce) {}
+    @media (prefers-contrast: more) {}
+
+    @media screen and (50px <= width <= 100px), (min-height: 100px) {}
+    `
+	const actual = analyze(fixture).atrules.media.features
+	const expected = {
+		total: 8,
+		totalUnique: 8,
+		unique: {
+			'min-width': 1,
+			'max-width': 1,
+			hover: 1,
+			'forced-colors': 1,
+			'prefers-color-scheme': 1,
+			'prefers-reduced-motion': 1,
+			'prefers-contrast': 1,
+			'min-height': 1,
+		},
+		uniquenessRatio: 8 / 8,
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('does not crash on incomplete @media queries', () => {
+	let css = `
+    @media (min-width) {}
+    @media (-moz-images-in-menus) {}
+    @media (min--moz-device-pixel-ratio) {}
+    @media (-ms-high-contrast), (-ms-high-contrast) {}
+    @media (min-resolution) {}
+    @media (-webkit-min-device-pixel-ratio) {}
+  `
+
+	expect(() => analyze(css)).not.toThrowError()
+})
+
+test('analyzes @keyframes', () => {
+	const fixture = `
+    @keyframes one {}
+    @keyframes one {}
+    @keyframes TWO {}
+
+    /* No prelude */
+    @keyframes {}
+
+    /* Prefixes */
+    @-webkit-keyframes animation {}
+    @-moz-keyframes animation {}
+    @-o-keyframes animation {}
+  `
+	const actual = analyze(fixture).atrules.keyframes
+	const expected = {
+		total: 6,
+		totalUnique: 5,
+		unique: {
+			'@keyframes one': 2,
+			'@keyframes TWO': 1,
+			'@-webkit-keyframes animation': 1,
+			'@-moz-keyframes animation': 1,
+			'@-o-keyframes animation': 1,
+		},
+		uniquenessRatio: 5 / 6,
+		prefixed: {
+			total: 3,
+			totalUnique: 3,
+			unique: {
+				'@-webkit-keyframes animation': 1,
+				'@-moz-keyframes animation': 1,
+				'@-o-keyframes animation': 1,
+			},
+			uniquenessRatio: 3 / 3,
+			ratio: 3 / 6,
+		},
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('counts ratio correctly when no @keyframes present', () => {
+	const fixture = `@media (min-width: 0px) {}`
+	const actual = analyze(fixture)
+	const expected = {
+		total: 0,
+		totalUnique: 0,
+		unique: {},
+		uniquenessRatio: 0,
+		prefixed: {
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+			ratio: 0,
+		},
+	}
+	expect(actual.atrules.keyframes).toEqual(expected)
+})
+
+test('analyzes container queries', () => {
+	// Fixture contains examples from the spec.
+	// https://drafts.csswg.org/css-contain-3/
+	const fixture = `
+    /* Example 2 */
+    @container (inline-size > 45em) {
+      .media-object {
+        grid-template: 'img content' auto / auto 1fr;
+      }
+    }
+
+    /* Example 3 */
+    @container (width > 40em) {
+      h2 { font-size: 1.5em; }
+    }
+
+    /* Example 4 */
+    @container (--cards) {
+      article {
+        border: thin solid silver;
+        border-radius: 0.5em;
+        padding: 1em;
+      }
+    }
+
+    /* Example 5 */
+    @container page-layout (block-size > 12em) {
+      .card { margin-block: 2em; }
+    }
+
+    @container component-library (inline-size > 30em) {
+      .card { margin-inline: 2em; }
+    }
+
+    /* Example 8 */
+    @container card (inline-size > 30em) and (--responsive = true) {
+      /* styles */
+    }
+
+    /* Example 11 */
+    @container type(inline-size) {
+      /* only applies when an inline-size container is available */
+      h2 { font-size: calc(1.2em + 1cqi); }
+    }
+
+    /* No prelude */
+    @container {}
+  `
+	const result = analyze(fixture)
+	const actual = result.atrules.container
+	const expected = {
+		total: 7,
+		totalUnique: 7,
+		unique: {
+			'(inline-size > 45em)': 1,
+			'(width > 40em)': 1,
+			'(--cards)': 1,
+			'page-layout (block-size > 12em)': 1,
+			'component-library (inline-size > 30em)': 1,
+			'card (inline-size > 30em) and (--responsive = true)': 1,
+			'type(inline-size)': 1,
+		},
+		uniquenessRatio: 7 / 7,
+		names: {
+			total: 3,
+			totalUnique: 3,
+			unique: {
+				card: 1,
+				'page-layout': 1,
+				'component-library': 1,
+			},
+			uniquenessRatio: 1 / 1,
+		},
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('finds named containers in @container', () => {
+	const fixture = `
+    @container test1 (inline-size > 30em) {}
+    @container test2 (inline-size > 30em) and style(--responsive: true) {}
+    @container style(--responsive: true) {}
+  `
+	const actual = analyze(fixture).atrules.container.names
+	const TOTAL = 2
+	const UNIQUE = 2
+	const expected = {
+		total: TOTAL,
+		totalUnique: TOTAL,
+		unique: {
+			test1: 1,
+			test2: 1,
+		},
+		uniquenessRatio: UNIQUE / TOTAL,
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('finds named containers in the `container-name` property', () => {
+	const fixture = `
+    a {
+      container-name: my-layout;
+      container-name: my-component;
+    }
+  `
+	const actual = analyze(fixture).atrules.container.names
+	const TOTAL = 2
+	const UNIQUE = 2
+	const expected = {
+		total: TOTAL,
+		totalUnique: TOTAL,
+		unique: {
+			'my-layout': 1,
+			'my-component': 1,
+		},
+		uniquenessRatio: UNIQUE / TOTAL,
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('finds named containers in the `container` shorthand', () => {
+	const fixture = `
+    a {
+      container: my-layout / size;
+      container: my-component / inline-size;
+    }
+  `
+	const actual = analyze(fixture).atrules.container.names
+	const TOTAL = 2
+	const UNIQUE = 2
+	const expected = {
+		total: TOTAL,
+		totalUnique: TOTAL,
+		unique: {
+			'my-layout': 1,
+			'my-component': 1,
+		},
+		uniquenessRatio: UNIQUE / TOTAL,
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('analyzes @property', () => {
+	const fixture = `
+    /* Examples from https://nerdy.dev/cant-break-this-design-system */
+    @property --focal-size {
+      syntax: '<length-percentage>';
+      initial-value: 100%;
+      inherits: false;
+    }
+
+    @property --hue {
+      syntax: '<angle>';
+      initial-value: .5turn;
+      inherits: false;
+    }
+
+    @property --surface {
+      syntax: '<color>';
+      initial-value: #333;
+      inherits: true;
+    }
+
+    @property --surface-over {
+      syntax: '<color>';
+      initial-value: #444;
+      inherits: true;
+    }
+
+    @property --surface-under {
+      syntax: '<color>';
+      initial-value: #222;
+      inherits: true;
+    }
+    /* end nerdy.dev examples */
+
+    @media all {
+      @layer test {
+        @property --test-dupe {
+          syntax: '<color>';
+          inherits: false;
+        }
+        @property --test-dupe {
+          syntax: '<color>';
+          inherits: false;
+        }
+      }
+    }
+
+    /* No prelude */
+    @property {}
+  `
+	const actual = analyze(fixture).atrules.property
+	const expected = {
+		total: 7,
+		totalUnique: 6,
+		unique: {
+			'--focal-size': 1,
+			'--hue': 1,
+			'--surface': 1,
+			'--surface-over': 1,
+			'--surface-under': 1,
+			'--test-dupe': 2,
+		},
+		uniquenessRatio: 6 / 7,
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('tracks nesting depth', () => {
+	const fixture = `
+    a {
+      color: red;
+    }
+
+    b {
+      color: green;
+
+      &:hover {
+        color: blue;
+      }
+
+      color: deepskyblue;
+
+      @container (width > 400px) {
+        color: rebeccapurple
+      }
+    }
+
+    @media print {
+      @supports (display: grid) {
+        c {
+          color: orange;
+        }
+      }
+    }
+  `
+	const actual = analyze(fixture).atrules.nesting
+	const expected = {
+		min: 0,
+		max: 1,
+		mean: 0.6666666666666666,
+		mode: 1,
+		range: 1,
+		sum: 2,
+		items: [1, 0, 1],
+		total: 3,
+		totalUnique: 2,
+		unique: {
+			0: 1,
+			1: 2,
+		},
+		uniquenessRatio: 2 / 3,
+	}
+	expect(actual).toEqual(expected)
+})
diff --git a/src/atrules/atrules.ts b/src/atrules/atrules.ts
new file mode 100644
index 00000000..651b842a
--- /dev/null
+++ b/src/atrules/atrules.ts
@@ -0,0 +1,79 @@
+import { strEquals, startsWith, endsWith } from '../string-utils.js'
+import { type Raw, walk, type AtrulePrelude, type Declaration } from 'css-tree'
+import { Identifier, MediaQuery } from '../css-tree-node-types.js'
+
+/**
+ * Check whether node.property === property and node.value === value,
+ * but case-insensitive and fast.
+ * @param property - The CSS property to compare with (case-insensitive)
+ * @param value - The identifier/keyword value to compare with
+ * @returns true if declaratioNode is the given property: value, false otherwise
+ */
+function isPropertyValue(node: Declaration, property: string, value: string): boolean {
+	// @ts-expect-error TODO: fix this
+	let firstChild = node.value.children.first
+	return strEquals(property, node.property) && firstChild.type === Identifier && strEquals(value, firstChild.name)
+}
+
+/**
+ * Check if an @supports atRule is a browserhack
+ * @returns true if the atrule is a browserhack
+ */
+export function isSupportsBrowserhack(prelude: AtrulePrelude | Raw): boolean {
+	let returnValue = false
+
+	walk(prelude, function (node) {
+		if (node.type === 'Declaration') {
+			if (isPropertyValue(node, '-webkit-appearance', 'none') || isPropertyValue(node, '-moz-appearance', 'meterbar')) {
+				returnValue = true
+				return this.break
+			}
+		}
+	})
+
+	return returnValue
+}
+
+/**
+ * Check if a @media atRule is a browserhack
+ * @returns true if the atrule is a browserhack
+ */
+export function isMediaBrowserhack(prelude: AtrulePrelude | Raw): boolean {
+	let returnValue = false
+
+	walk(prelude, function (node) {
+		// @ts-expect-error outdated css-tree types
+		let { mediaType, name, value, type, kind } = node
+
+		if (type === MediaQuery && mediaType !== null) {
+			// Note: CSSTree adds a trailing space to \\9
+			if (startsWith('\\0', mediaType) || endsWith('\\9 ', mediaType)) {
+				returnValue = true
+				return this.break
+			}
+			// @ts-expect-error outdated css-tree types
+		} else if (type === 'Feature' && kind === 'media') {
+			if (value && value.unit && value.unit === '\\0') {
+				returnValue = true
+				return this.break
+			} else if (
+				strEquals('-moz-images-in-menus', name) ||
+				strEquals('min--moz-device-pixel-ratio', name) ||
+				strEquals('-ms-high-contrast', name)
+			) {
+				returnValue = true
+				return this.break
+			} else if (strEquals('min-resolution', name) && value && strEquals('.001', value.value) && strEquals('dpcm', value.unit)) {
+				returnValue = true
+				return this.break
+			} else if (strEquals('-webkit-min-device-pixel-ratio', name)) {
+				if (value && value.value && (strEquals('0', value.value) || strEquals('10000', value.value))) {
+					returnValue = true
+					return this.break
+				}
+			}
+		}
+	})
+
+	return returnValue
+}
diff --git a/src/collection.js b/src/collection.js
deleted file mode 100644
index f67135b8..00000000
--- a/src/collection.js
+++ /dev/null
@@ -1,111 +0,0 @@
-export class Collection {
-	/** @param {boolean} useLocations */
-	constructor(useLocations = false) {
-		/** @type {Map<string, number[]>} */
-		this._items = new Map()
-		this._total = 0
-
-		if (useLocations) {
-			/** @type {number[]} */
-			this._nodes = []
-		}
-
-		/** @type {boolean} */
-		this._useLocations = useLocations
-	}
-
-	/**
-	 * @param {string | number} item
-	 * @param {import('css-tree').CssLocation} node_location
-	 */
-	p(item, node_location) {
-		let index = this._total
-
-		if (this._useLocations) {
-			let start = node_location.start
-			let start_offset = start.offset
-			let position = index * 4
-
-			this._nodes[position] = start.line
-			this._nodes[position + 1] = start.column
-			this._nodes[position + 2] = start_offset
-			this._nodes[position + 3] = node_location.end.offset - start_offset
-		}
-
-		if (this._items.has(item)) {
-			/** @type number[] */
-			let list = this._items.get(item)
-			list.push(index)
-			this._total++
-			return
-		}
-
-		this._items.set(item, [index])
-		this._total++
-	}
-
-	size() {
-		return this._total
-	}
-
-	/**
-	 * @typedef CssLocation
-	 * @property {number} line
-	 * @property {number} column
-	 * @property {number} offset
-	 * @property {number} length
-	 *
-	 * @returns {{
-	 * 	total: number;
-	 * 	totalUnique: number;
-	 * 	uniquenessRatio: number;
-	 * 	unique: Record<string, number>;
-	 * } & ({
-	 * 	uniqueWithLocations: Record<string, CssLocation[]>
-	 * } | {
-	 * 	uniqueWithLocations?: undefined
-	 * })}
-	 */
-	c() {
-		/** @type {Map<string, CssLocation[]>} */
-		let uniqueWithLocations = new Map()
-		/** @type {Record<string, number>} */
-		let unique = {}
-		let useLocations = this._useLocations
-		let items = this._items
-		let _nodes = this._nodes
-		let size = items.size
-
-		items.forEach((list, key) => {
-			if (useLocations) {
-				let nodes = list.map(function (index) {
-					let position = index * 4
-					/** @type {CssLocation} */
-					return {
-						line: _nodes[position],
-						column: _nodes[position + 1],
-						offset: _nodes[position + 2],
-						length: _nodes[position + 3],
-					}
-				})
-				uniqueWithLocations.set(key, nodes)
-			} else {
-				unique[key] = list.length
-			}
-		})
-
-		let total = this._total
-		let data = {
-			total,
-			totalUnique: size,
-			unique,
-			uniquenessRatio: total === 0 ? 0 : size / total,
-		}
-
-		if (useLocations) {
-			data.uniqueWithLocations = Object.fromEntries(uniqueWithLocations)
-		}
-
-		return data
-	}
-}
diff --git a/src/collection.ts b/src/collection.ts
new file mode 100644
index 00000000..6400c025
--- /dev/null
+++ b/src/collection.ts
@@ -0,0 +1,85 @@
+import type { CssLocation } from 'css-tree'
+
+export class Collection {
+	#items: Map<string | number, number[]>
+	#total: number
+	#nodes: number[] = []
+	#useLocations: boolean
+
+	constructor(useLocations = false) {
+		this.#items = new Map()
+		this.#total = 0
+
+		if (useLocations) {
+			this.#nodes = []
+		}
+
+		this.#useLocations = useLocations
+	}
+
+	p(item: string | number, node_location: { start: { line: number; column: number; offset: number }; end: { offset: number } }) {
+		let index = this.#total
+
+		if (this.#useLocations) {
+			let start = node_location.start
+			let start_offset = start.offset
+			let position = index * 4
+
+			this.#nodes[position] = start.line
+			this.#nodes[position + 1] = start.column
+			this.#nodes[position + 2] = start_offset
+			this.#nodes[position + 3] = node_location.end.offset - start_offset
+		}
+
+		if (this.#items.has(item)) {
+			let list = this.#items.get(item)!
+			list.push(index)
+			this.#total++
+			return
+		}
+
+		this.#items.set(item, [index])
+		this.#total++
+	}
+
+	size() {
+		return this.#total
+	}
+
+	c() {
+		let uniqueWithLocations: Map<string | number, { line: number; column: number; offset: number; length: number }[]> = new Map()
+		let unique: Record<string, number> = {}
+		let useLocations = this.#useLocations
+		let items = this.#items
+		let _nodes = this.#nodes
+		let size = items.size
+
+		items.forEach((list, key) => {
+			if (useLocations) {
+				let nodes = list.map(function (index) {
+					let position = index * 4
+					return {
+						line: _nodes[position]!,
+						column: _nodes[position + 1]!,
+						offset: _nodes[position + 2]!,
+						length: _nodes[position + 3]!,
+					}
+				})
+				uniqueWithLocations.set(key, nodes)
+			} else {
+				unique[key] = list.length
+			}
+		})
+
+		let total = this.#total
+		let data = {
+			total,
+			totalUnique: size,
+			unique,
+			uniquenessRatio: total === 0 ? 0 : size / total,
+			uniqueWithLocations: useLocations ? Object.fromEntries(uniqueWithLocations) : undefined,
+		}
+
+		return data
+	}
+}
diff --git a/src/context-collection.js b/src/context-collection.js
deleted file mode 100644
index 35495408..00000000
--- a/src/context-collection.js
+++ /dev/null
@@ -1,52 +0,0 @@
-import { Collection } from './collection.js'
-
-class ContextCollection {
-  /** @param {boolean} useLocations */
-  constructor(useLocations) {
-    this._list = new Collection(useLocations)
-    /** @type {Map<string, Collection>} */
-    this._contexts = new Map()
-    /** @type {boolean} */
-    this._useLocations = useLocations
-  }
-
-  /**
-   * Add an item to this _list's context
-   * @param {string} item Item to push
-   * @param {string} context Context to push Item to
-   * @param {import('css-tree').CssLocation} node_location
-   */
-  push(item, context, node_location) {
-    this._list.p(item, node_location)
-
-    if (!this._contexts.has(context)) {
-      this._contexts.set(context, new Collection(this._useLocations))
-    }
-
-    this._contexts.get(context).p(item, node_location)
-  }
-
-  count() {
-    /**
-     * @type {Map<string, {
-     * total: number,
-     * totalUnique: number,
-     * unique: Record<string, number>,
-     * uniquenessRatio: number
-     * }>}
-     */
-    let itemsPerContext = new Map()
-
-    for (let [context, value] of this._contexts.entries()) {
-      itemsPerContext.set(context, value.c())
-    }
-
-    return Object.assign(this._list.c(), {
-      itemsPerContext: Object.fromEntries(itemsPerContext)
-    })
-  }
-}
-
-export {
-  ContextCollection
-}
\ No newline at end of file
diff --git a/src/context-collection.ts b/src/context-collection.ts
new file mode 100644
index 00000000..45fd9e87
--- /dev/null
+++ b/src/context-collection.ts
@@ -0,0 +1,42 @@
+import type { CssLocation } from 'css-tree'
+import { Collection } from './collection.js'
+
+export class ContextCollection {
+	#list: Collection
+	#contexts: Map<string, Collection>
+	#useLocations: boolean
+
+	constructor(useLocations: boolean) {
+		this.#list = new Collection(useLocations)
+		this.#contexts = new Map()
+		this.#useLocations = useLocations
+	}
+
+	/**
+	 * Add an item to this #list's context
+	 * @param item Item to push
+	 * @param context Context to push Item to
+	 * @param node_location
+	 */
+	push(item: string, context: string, node_location: CssLocation) {
+		this.#list.p(item, node_location)
+
+		if (!this.#contexts.has(context)) {
+			this.#contexts.set(context, new Collection(this.#useLocations))
+		}
+
+		this.#contexts.get(context)!.p(item, node_location)
+	}
+
+	count() {
+		let itemsPerContext = new Map()
+
+		for (let [context, value] of this.#contexts.entries()) {
+			itemsPerContext.set(context, value.c())
+		}
+
+		return Object.assign(this.#list.c(), {
+			itemsPerContext: Object.fromEntries(itemsPerContext),
+		})
+	}
+}
diff --git a/src/css-tree-node-types.js b/src/css-tree-node-types.ts
similarity index 100%
rename from src/css-tree-node-types.js
rename to src/css-tree-node-types.ts
diff --git a/src/declarations/declarations.test.js b/src/declarations/declarations.test.ts
similarity index 52%
rename from src/declarations/declarations.test.js
rename to src/declarations/declarations.test.ts
index 102ce36f..6d217469 100644
--- a/src/declarations/declarations.test.js
+++ b/src/declarations/declarations.test.ts
@@ -1,22 +1,19 @@
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
+import { test, expect } from 'vitest'
 import { analyze } from '../index.js'
 
-const Declarations = suite('Declarations')
-
-Declarations('handles empty values', () => {
-  let css = `
+test('handles empty values', () => {
+	let css = `
     thing {
       height:;
       width: ;
     }
   `
 
-  assert.not.throws(() => analyze(css))
+	expect(() => analyze(css)).not.toThrowError()
 })
 
-Declarations('should be counted', () => {
-  const fixture = `
+test('should be counted', () => {
+	const fixture = `
     rule {
       color: green;
       color: orange !important;
@@ -45,15 +42,15 @@ Declarations('should be counted', () => {
       }
     }
   `
-  const actual = analyze(fixture).declarations
+	const actual = analyze(fixture).declarations
 
-  assert.is(actual.total, 6)
-  assert.is(actual.totalUnique, 5)
-  assert.is(actual.uniquenessRatio, 5 / 6)
+	expect(actual.total).toEqual(6)
+	expect(actual.totalUnique).toEqual(5)
+	expect(actual.uniquenessRatio).toEqual(5 / 6)
 })
 
-Declarations('should count !importants', () => {
-  const fixture = `
+test('should count !importants', () => {
+	const fixture = `
     some {
       color: red;
       color: red: !important;
@@ -82,25 +79,25 @@ Declarations('should count !importants', () => {
       }
     }
   `
-  const actual = analyze(fixture).declarations.importants
-  const expected = {
-    total: 4,
-    ratio: 0.5,
-    inKeyframes: {
-      total: 0,
-      ratio: 0
-    }
-  }
-
-  assert.equal(actual, expected)
+	const actual = analyze(fixture).declarations.importants
+	const expected = {
+		total: 4,
+		ratio: 0.5,
+		inKeyframes: {
+			total: 0,
+			ratio: 0,
+		},
+	}
+
+	expect(actual).toEqual(expected)
 })
 
 /**
  * @see https://drafts.csswg.org/css-animations-1/#keyframes
  * @see https://developer.mozilla.org/en-US/docs/Web/CSS/@keyframes#!important_in_a_keyframe
  */
-Declarations('should calculate !importants within @keyframes', () => {
-  const fixture = `
+test('should calculate !importants within @keyframes', () => {
+	const fixture = `
     test1 {
       color: green !important;
     }
@@ -111,18 +108,18 @@ Declarations('should calculate !importants within @keyframes', () => {
       }
     }
   `
-  const result = analyze(fixture)
-  const actual = result.declarations.importants
-
-  assert.is(actual.total, 2)
-  assert.equal(actual.inKeyframes, {
-    total: 1,
-    ratio: 1 / 2
-  })
+	const result = analyze(fixture)
+	const actual = result.declarations.importants
+
+	expect(actual.total).toEqual(2)
+	expect(actual.inKeyframes).toEqual({
+		total: 1,
+		ratio: 1 / 2,
+	})
 })
 
-Declarations('should count complexity', () => {
-  const css = `
+test('should count complexity', () => {
+	const css = `
     a {
       color: green;
       color: green !important;
@@ -134,20 +131,20 @@ Declarations('should count complexity', () => {
       }
     }
   `
-  const actual = analyze(css).declarations.complexity
-  const expected = {
-    min: 1,
-    max: 3,
-    mean: 2,
-    mode: 2,
-    range: 2,
-    sum: 6,
-  }
-  assert.equal(actual, expected)
+	const actual = analyze(css).declarations.complexity
+	const expected = {
+		min: 1,
+		max: 3,
+		mean: 2,
+		mode: 2,
+		range: 2,
+		sum: 6,
+	}
+	expect(actual).toEqual(expected)
 })
 
-Declarations('tracks nesting depth', () => {
-  const fixture = `
+test('tracks nesting depth', () => {
+	const fixture = `
     a {
       color: red;
     }
@@ -174,25 +171,23 @@ Declarations('tracks nesting depth', () => {
       }
     }
   `
-  const actual = analyze(fixture).declarations.nesting
-  const expected = {
-    min: 0,
-    max: 2,
-    mean: 0.6666666666666666,
-    mode: 0,
-    range: 2,
-    sum: 4,
-    items: [0, 0, 1, 0, 1, 2],
-    total: 6,
-    totalUnique: 3,
-    unique: {
-      0: 3,
-      1: 2,
-      2: 1,
-    },
-    uniquenessRatio: 3 / 6,
-  }
-  assert.equal(actual, expected)
+	const actual = analyze(fixture).declarations.nesting
+	const expected = {
+		min: 0,
+		max: 2,
+		mean: 0.6666666666666666,
+		mode: 0,
+		range: 2,
+		sum: 4,
+		items: [0, 0, 1, 0, 1, 2],
+		total: 6,
+		totalUnique: 3,
+		unique: {
+			0: 3,
+			1: 2,
+			2: 1,
+		},
+		uniquenessRatio: 3 / 6,
+	}
+	expect(actual).toEqual(expected)
 })
-
-Declarations.run()
\ No newline at end of file
diff --git a/src/index.js b/src/index.js
deleted file mode 100644
index 6d2a2268..00000000
--- a/src/index.js
+++ /dev/null
@@ -1,1097 +0,0 @@
-import parse from 'css-tree/parser'
-import walk from 'css-tree/walker'
-import { calculateForAST } from '@bramus/specificity/core'
-import { isSupportsBrowserhack, isMediaBrowserhack } from './atrules/atrules.js'
-import { getCombinators, getComplexity, isAccessibility, isPrefixed, hasPseudoClass } from './selectors/utils.js'
-import { colorFunctions, colorKeywords, namedColors, systemColors } from './values/colors.js'
-import { destructure, isSystemFont } from './values/destructure-font-shorthand.js'
-import { isValueKeyword, keywords, isValueReset } from './values/values.js'
-import { analyzeAnimation } from './values/animations.js'
-import { isValuePrefixed } from './values/vendor-prefix.js'
-import { ContextCollection } from './context-collection.js'
-import { Collection } from './collection.js'
-import { AggregateCollection } from './aggregate-collection.js'
-import { strEquals, startsWith, endsWith } from './string-utils.js'
-import { hasVendorPrefix } from './vendor-prefix.js'
-import { isCustom, isHack, isProperty } from './properties/property-utils.js'
-import { getEmbedType } from './stylesheet/stylesheet.js'
-import { isIe9Hack } from './values/browserhacks.js'
-import { basename } from './properties/property-utils.js'
-import {
-  Atrule,
-  Selector,
-  Dimension,
-  Url,
-  Value,
-  Declaration,
-  Hash,
-  Rule,
-  Identifier,
-  Func,
-  Operator
-} from './css-tree-node-types.js'
-import { KeywordSet } from './keyword-set.js'
-
-/** @typedef {[number, number, number]} Specificity */
-
-let border_radius_properties = new KeywordSet([
-  'border-radius',
-  'border-top-left-radius',
-  'border-top-right-radius',
-  'border-bottom-right-radius',
-  'border-bottom-left-radius',
-  'border-start-start-radius',
-  'border-start-end-radius',
-  'border-end-end-radius',
-  'border-end-start-radius',
-])
-
-function ratio(part, total) {
-  if (total === 0) return 0
-  return part / total
-}
-
-let defaults = {
-  useLocations: false
-}
-
-/**
- * @typedef Options
- * @property {boolean} useLocations Use Locations (`{ 'item': [{ line, column, offset, length }] }`) instead of a regular count per occurrence (`{ 'item': 3 }`)
- */
-
-/**
- * Analyze CSS
- * @param {string} css
- * @param {Options} options
- */
-export function analyze(css, options = {}) {
-  let settings = Object.assign({}, defaults, options)
-  let useLocations = settings.useLocations === true
-  let start = Date.now()
-
-  /**
-   * Recreate the authored CSS from a CSSTree node
-   * @param {import('css-tree').CssNode} node - Node from CSSTree AST to stringify
-   * @returns {string} str - The stringified node
-   */
-  function stringifyNode(node) {
-    return stringifyNodePlain(node).trim()
-  }
-
-  function stringifyNodePlain(node) {
-    let loc = node.loc
-    return css.substring(loc.start.offset, loc.end.offset)
-  }
-
-  // Stylesheet
-  let totalComments = 0
-  let commentsSize = 0
-  let embedSize = 0
-  let embedTypes = {
-    total: 0,
-    /** @type {Map<string, { size: number, count: number } & ({ uniqueWithLocations?: undefined } | ({ uniqueWithLocations: { offset: number, line: number, column: number, length: number }[] })) }>} */
-    unique: new Map()
-  }
-
-  let startParse = Date.now()
-
-  let ast = parse(css, {
-    parseCustomProperty: true, // To find font-families, colors, etc.
-    positions: true, // So we can use stringifyNode()
-    /** @param {string} comment */
-    onComment: function (comment) {
-      totalComments++
-      commentsSize += comment.length
-    },
-  })
-
-  let startAnalysis = Date.now()
-  let linesOfCode = ast.loc.end.line - ast.loc.start.line + 1
-
-  // Atrules
-  let atrules = new Collection(useLocations)
-  let atRuleComplexities = new AggregateCollection()
-  /** @type {Record<string, string>[]} */
-  let fontfaces = []
-  let fontfaces_with_loc = new Collection(useLocations)
-  let layers = new Collection(useLocations)
-  let imports = new Collection(useLocations)
-  let medias = new Collection(useLocations)
-  let mediaBrowserhacks = new Collection(useLocations)
-  let mediaFeatures = new Collection(useLocations)
-  let charsets = new Collection(useLocations)
-  let supports = new Collection(useLocations)
-  let supportsBrowserhacks = new Collection(useLocations)
-  let keyframes = new Collection(useLocations)
-  let prefixedKeyframes = new Collection(useLocations)
-  let containers = new Collection(useLocations)
-  let containerNames = new Collection(useLocations)
-  let registeredProperties = new Collection(useLocations)
-  let atruleNesting = new AggregateCollection()
-  let uniqueAtruleNesting = new Collection(useLocations)
-
-  // Rules
-  let totalRules = 0
-  let emptyRules = 0
-  let ruleSizes = new AggregateCollection()
-  let selectorsPerRule = new AggregateCollection()
-  let declarationsPerRule = new AggregateCollection()
-  let uniqueRuleSize = new Collection(useLocations)
-  let uniqueSelectorsPerRule = new Collection(useLocations)
-  let uniqueDeclarationsPerRule = new Collection(useLocations)
-  let ruleNesting = new AggregateCollection()
-  let uniqueRuleNesting = new Collection(useLocations)
-
-  // Selectors
-  let keyframeSelectors = new Collection(useLocations)
-  let uniqueSelectors = new Set()
-  let prefixedSelectors = new Collection(useLocations)
-  /** @type {Specificity} */
-  let maxSpecificity
-  /** @type {Specificity} */
-  let minSpecificity
-  let specificityA = new AggregateCollection()
-  let specificityB = new AggregateCollection()
-  let specificityC = new AggregateCollection()
-  let uniqueSpecificities = new Collection(useLocations)
-  let selectorComplexities = new AggregateCollection()
-  let uniqueSelectorComplexities = new Collection(useLocations)
-  /** @type {Specificity[]} */
-  let specificities = []
-  let ids = new Collection(useLocations)
-  let a11y = new Collection(useLocations)
-  let pseudoClasses = new Collection(useLocations)
-  let combinators = new Collection(useLocations)
-  let selectorNesting = new AggregateCollection()
-  let uniqueSelectorNesting = new Collection(useLocations)
-
-  // Declarations
-  let uniqueDeclarations = new Set()
-  let totalDeclarations = 0
-  let declarationComplexities = new AggregateCollection()
-  let importantDeclarations = 0
-  let importantsInKeyframes = 0
-  let importantCustomProperties = new Collection(useLocations)
-  let declarationNesting = new AggregateCollection()
-  let uniqueDeclarationNesting = new Collection(useLocations)
-
-  // Properties
-  let properties = new Collection(useLocations)
-  let propertyHacks = new Collection(useLocations)
-  let propertyVendorPrefixes = new Collection(useLocations)
-  let customProperties = new Collection(useLocations)
-  let propertyComplexities = new AggregateCollection()
-
-  // Values
-  let valueComplexities = new AggregateCollection()
-  let vendorPrefixedValues = new Collection(useLocations)
-  let valueBrowserhacks = new Collection(useLocations)
-  let zindex = new Collection(useLocations)
-  let textShadows = new Collection(useLocations)
-  let boxShadows = new Collection(useLocations)
-  let fontFamilies = new Collection(useLocations)
-  let fontSizes = new Collection(useLocations)
-  let lineHeights = new Collection(useLocations)
-  let timingFunctions = new Collection(useLocations)
-  let durations = new Collection(useLocations)
-  let colors = new ContextCollection(useLocations)
-  let colorFormats = new Collection(useLocations)
-  let units = new ContextCollection(useLocations)
-  let gradients = new Collection(useLocations)
-  let valueKeywords = new Collection(useLocations)
-  let borderRadiuses = new ContextCollection(useLocations)
-  let resets = new Collection(useLocations)
-
-  let nestingDepth = 0
-
-  walk(ast, {
-    enter(node) {
-      switch (node.type) {
-        case Atrule: {
-          atrules.p(node.name, node.loc)
-          atruleNesting.push(nestingDepth)
-          uniqueAtruleNesting.p(nestingDepth, node.loc)
-
-          let atRuleName = node.name
-
-          if (atRuleName === 'font-face') {
-            let descriptors = {}
-
-            if (useLocations) {
-              fontfaces_with_loc.p(node.loc.start.offset, node.loc)
-            }
-
-            node.block.children.forEach(descriptor => {
-              // Ignore 'Raw' nodes in case of CSS syntax errors
-              if (descriptor.type === Declaration) {
-                descriptors[descriptor.property] = stringifyNode(descriptor.value)
-              }
-            })
-
-            fontfaces.push(descriptors)
-            atRuleComplexities.push(1)
-            break
-          }
-
-          let complexity = 1
-
-          // All the AtRules in here MUST have a prelude, so we can count their names
-          if (node.prelude !== null) {
-            let prelude = node.prelude
-            let preludeStr = prelude && stringifyNode(node.prelude)
-            let loc = prelude.loc
-
-            if (atRuleName === 'media') {
-              medias.p(preludeStr, loc)
-              if (isMediaBrowserhack(prelude)) {
-                mediaBrowserhacks.p(preludeStr, loc)
-                complexity++
-              }
-            } else if (atRuleName === 'supports') {
-              supports.p(preludeStr, loc)
-              // TODO: analyze vendor prefixes in @supports
-              // TODO: analyze complexity of @supports 'declaration'
-              if (isSupportsBrowserhack(prelude)) {
-                supportsBrowserhacks.p(preludeStr, loc)
-                complexity++
-              }
-            } else if (endsWith('keyframes', atRuleName)) {
-              let name = '@' + atRuleName + ' ' + preludeStr
-              if (hasVendorPrefix(atRuleName)) {
-                prefixedKeyframes.p(name, loc)
-                complexity++
-              }
-              keyframes.p(name, loc)
-            } else if (atRuleName === 'import') {
-              walk(node, function (prelude_node) {
-                if (prelude_node.type === 'Condition' && prelude_node.kind === 'supports') {
-                  let prelude = stringifyNode(prelude_node)
-
-                  supports.p(prelude, prelude_node.loc)
-                  return this.break
-                }
-              })
-              imports.p(preludeStr, loc)
-              // TODO: analyze complexity of media queries, layers and supports in @import
-              // see https://github.com/projectwallace/css-analyzer/issues/326
-            } else if (atRuleName === 'charset') {
-              charsets.p(preludeStr, loc)
-            } else if (atRuleName === 'container') {
-              containers.p(preludeStr, loc)
-
-              if (prelude.children.first?.type === 'Identifier') {
-                let containerName = prelude.children.first.name
-                containerNames.p(containerName, loc)
-              }
-              // TODO: calculate complexity of container 'declaration'
-            } else if (atRuleName === 'property') {
-              registeredProperties.p(preludeStr, loc)
-              // TODO: add complexity for descriptors
-            }
-          } else {
-            if (atRuleName === 'layer') {
-              layers.p('<anonymous>', node.loc)
-              complexity++
-            }
-          }
-          atRuleComplexities.push(complexity)
-          break
-        }
-        case 'Layer': {
-          if (node.name !== null) {
-            layers.p(node.name, node.loc)
-          }
-          break
-        }
-        case 'Feature': {
-          mediaFeatures.p(node.name, node.loc)
-          break
-        }
-        case Rule: {
-          let prelude = node.prelude
-          let block = node.block
-          let preludeChildren = prelude.children
-          let blockChildren = block.children
-          let numSelectors = preludeChildren ? preludeChildren.size : 0
-          let numDeclarations = blockChildren ? blockChildren.size : 0
-
-          ruleSizes.push(numSelectors + numDeclarations)
-          uniqueRuleSize.p(numSelectors + numDeclarations, node.loc)
-          selectorsPerRule.push(numSelectors)
-          uniqueSelectorsPerRule.p(numSelectors, prelude.loc)
-          declarationsPerRule.push(numDeclarations)
-          uniqueDeclarationsPerRule.p(numDeclarations, block.loc)
-          ruleNesting.push(nestingDepth)
-          uniqueRuleNesting.p(nestingDepth, node.loc)
-
-          totalRules++
-
-          if (numDeclarations === 0) {
-            emptyRules++
-          }
-          break
-        }
-        case Selector: {
-          let selector = stringifyNode(node)
-
-          if (this.atrule && endsWith('keyframes', this.atrule.name)) {
-            keyframeSelectors.p(selector, node.loc)
-            return this.skip
-          }
-
-          if (isAccessibility(node)) {
-            a11y.p(selector, node.loc)
-          }
-
-          let pseudos = hasPseudoClass(node)
-          if (pseudos !== false) {
-            for (let pseudo of pseudos) {
-              pseudoClasses.p(pseudo, node.loc)
-            }
-          }
-
-          let complexity = getComplexity(node)
-
-          if (isPrefixed(node)) {
-            prefixedSelectors.p(selector, node.loc)
-          }
-
-          uniqueSelectors.add(selector)
-          selectorComplexities.push(complexity)
-          uniqueSelectorComplexities.p(complexity, node.loc)
-          selectorNesting.push(nestingDepth - 1)
-          uniqueSelectorNesting.p(nestingDepth - 1, node.loc)
-
-          // #region specificity
-          let specificity = calculateForAST(node).toArray()
-          let [sa, sb, sc] = specificity
-
-          uniqueSpecificities.p(specificity.toString(), node.loc)
-
-          specificityA.push(sa)
-          specificityB.push(sb)
-          specificityC.push(sc)
-
-          if (maxSpecificity === undefined) {
-            maxSpecificity = specificity
-          }
-
-          if (minSpecificity === undefined) {
-            minSpecificity = specificity
-          }
-
-          if (minSpecificity !== undefined && compareSpecificity(minSpecificity, specificity) < 0) {
-            minSpecificity = specificity
-          }
-
-          if (maxSpecificity !== undefined && compareSpecificity(maxSpecificity, specificity) > 0) {
-            maxSpecificity = specificity
-          }
-
-          specificities.push(specificity)
-          // #endregion
-
-          if (sa > 0) {
-            ids.p(selector, node.loc)
-          }
-
-          getCombinators(node, function onCombinator(combinator) {
-            combinators.p(combinator.name, combinator.loc)
-          })
-
-          // Avoid deeper walking of selectors to not mess with
-          // our specificity calculations in case of a selector
-          // with :where() or :is() that contain SelectorLists
-          // as children
-          return this.skip
-        }
-        case Dimension: {
-          if (!this.declaration) {
-            break
-          }
-
-          /** @type {string} */
-          let unit = node.unit
-
-          if (endsWith('\\9', unit)) {
-            units.push(unit.substring(0, unit.length - 2), this.declaration.property, node.loc)
-          } else {
-            units.push(unit, this.declaration.property, node.loc)
-          }
-
-          return this.skip
-        }
-        case Url: {
-          if (startsWith('data:', node.value)) {
-            let embed = node.value
-            let size = embed.length
-            let type = getEmbedType(embed)
-
-            embedTypes.total++
-            embedSize += size
-
-            let loc = {
-              /** @type {number} */
-              line: node.loc.start.line,
-              /** @type {number} */
-              column: node.loc.start.column,
-              /** @type {number} */
-              offset: node.loc.start.offset,
-              /** @type {number} */
-              length: node.loc.end.offset - node.loc.start.offset,
-            }
-
-            if (embedTypes.unique.has(type)) {
-              let item = embedTypes.unique.get(type)
-              item.count++
-              item.size += size
-              embedTypes.unique.set(type, item)
-              if (useLocations) {
-                item.uniqueWithLocations.push(loc)
-              }
-            } else {
-              let item = {
-                count: 1,
-                size
-              }
-              if (useLocations) {
-                item.uniqueWithLocations = [loc]
-              }
-              embedTypes.unique.set(type, item)
-            }
-          }
-          break
-        }
-        case Value: {
-          if (isValueKeyword(node)) {
-            valueComplexities.push(1)
-            valueKeywords.p(stringifyNode(node), node.loc)
-            break
-          }
-
-          /** @type {import('css-tree').Declaration} */
-          let declaration = this.declaration
-          let { property, important } = declaration
-          let complexity = 1
-
-          // i.e. `background-image: -webkit-linear-gradient()`
-          if (isValuePrefixed(node)) {
-            vendorPrefixedValues.p(stringifyNode(node), node.loc)
-            complexity++
-          }
-
-          // i.e. `property: value !ie`
-          if (typeof important === 'string') {
-            valueBrowserhacks.p(stringifyNodePlain(node) + '!' + important, node.loc)
-            complexity++
-          }
-
-          // i.e. `property: value\9`
-          if (isIe9Hack(node)) {
-            valueBrowserhacks.p(stringifyNode(node), node.loc)
-            complexity++
-          }
-
-          let children = node.children
-          let loc = node.loc
-
-          // TODO: should shorthands be counted towards complexity?
-          valueComplexities.push(complexity)
-
-          // Process properties first that don't have colors,
-          // so we can avoid further walking them;
-          if (
-            isProperty('margin', property) ||
-            isProperty('margin-block', property) ||
-            isProperty('margin-inline', property) ||
-            isProperty('margin-top', property) ||
-            isProperty('margin-right', property) ||
-            isProperty('margin-bottom', property) ||
-            isProperty('margin-left', property) ||
-            isProperty('padding', property) ||
-            isProperty('padding-block', property) ||
-            isProperty('padding-inline', property) ||
-            isProperty('padding-top', property) ||
-            isProperty('padding-right', property) ||
-            isProperty('padding-bottom', property) ||
-            isProperty('padding-left', property)
-          ) {
-            if (isValueReset(node)) {
-              resets.p(property, declaration.loc)
-            }
-          }
-          else if (isProperty('z-index', property)) {
-            zindex.p(stringifyNode(node), loc)
-            return this.skip
-          }
-          else if (isProperty('font', property)) {
-            if (isSystemFont(node)) return
-
-            let result = destructure(node, stringifyNode, function (item) {
-              if (item.type === 'keyword') {
-                valueKeywords.p(item.value, loc)
-              }
-            })
-
-            if (!result) {
-              return this.skip
-            }
-
-            let { font_size, line_height, font_family } = result
-            if (font_family) {
-              fontFamilies.p(font_family, loc)
-            }
-
-            if (font_size) {
-              fontSizes.p(font_size, loc)
-            }
-
-            if (line_height) {
-              lineHeights.p(line_height, loc)
-            }
-
-            break
-          }
-          else if (isProperty('font-size', property)) {
-            if (!isSystemFont(node)) {
-              fontSizes.p(stringifyNode(node), loc)
-            }
-            break
-          }
-          else if (isProperty('font-family', property)) {
-            if (!isSystemFont(node)) {
-              fontFamilies.p(stringifyNode(node), loc)
-            }
-            break
-          }
-          else if (isProperty('line-height', property)) {
-            lineHeights.p(stringifyNode(node), loc)
-          }
-          else if (isProperty('transition', property) || isProperty('animation', property)) {
-            analyzeAnimation(children, function (item) {
-              if (item.type === 'fn') {
-                timingFunctions.p(stringifyNode(item.value), loc)
-              }
-              else if (item.type === 'duration') {
-                durations.p(stringifyNode(item.value), loc)
-              }
-              else if (item.type === 'keyword') {
-                valueKeywords.p(stringifyNode(item.value), loc)
-              }
-            })
-            break
-          }
-          else if (isProperty('animation-duration', property) || isProperty('transition-duration', property)) {
-            if (children && children.size > 1) {
-              children.forEach(child => {
-                if (child.type !== Operator) {
-                  durations.p(stringifyNode(child), loc)
-                }
-              })
-            }
-            else {
-              durations.p(stringifyNode(node), loc)
-            }
-            break
-          }
-          else if (isProperty('transition-timing-function', property) || isProperty('animation-timing-function', property)) {
-            if (children && children.size > 1) {
-              children.forEach(child => {
-                if (child.type !== Operator) {
-                  timingFunctions.p(stringifyNode(child), loc)
-                }
-              })
-            }
-            else {
-              timingFunctions.p(stringifyNode(node), loc)
-            }
-            break
-          }
-          else if (isProperty('container-name', property)) {
-            containerNames.p(stringifyNode(node), loc)
-          }
-          else if (isProperty('container', property)) {
-            // The first identifier is the container name
-            // Example: container: my-layout / inline-size;
-            if (children.first?.type === 'Identifier') {
-              containerNames.p(children.first.name, loc)
-            }
-          }
-          else if (border_radius_properties.has(basename(property))) {
-            if (!isValueKeyword(node)) {
-              borderRadiuses.push(stringifyNode(node), property, loc)
-            }
-            break
-          }
-          else if (isProperty('text-shadow', property)) {
-            if (!isValueKeyword(node)) {
-              textShadows.p(stringifyNode(node), loc)
-            }
-            // no break here: potentially contains colors
-          }
-          else if (isProperty('box-shadow', property)) {
-            if (!isValueKeyword(node)) {
-              boxShadows.p(stringifyNode(node), loc)
-            }
-            // no break here: potentially contains colors
-          }
-
-          walk(node, function (valueNode) {
-            let nodeName = valueNode.name
-
-            switch (valueNode.type) {
-              case Hash: {
-                let hexLength = valueNode.value.length
-                if (endsWith('\\9', valueNode.value)) {
-                  hexLength = hexLength - 2
-                }
-                colors.push('#' + valueNode.value, property, loc)
-                colorFormats.p(`hex` + hexLength, loc)
-
-                return this.skip
-              }
-              case Identifier: {
-                if (keywords.has(nodeName)) {
-                  valueKeywords.p(nodeName, loc)
-                }
-
-                // Bail out if it can't be a color name
-                // 20 === 'lightgoldenrodyellow'.length
-                // 3 === 'red'.length
-                let nodeLen = nodeName.length
-                if (nodeLen > 20 || nodeLen < 3) {
-                  return this.skip
-                }
-
-                // A keyword is most likely to be 'transparent' or 'currentColor'
-                if (colorKeywords.has(nodeName)) {
-                  let stringified = stringifyNode(valueNode)
-                  colors.push(stringified, property, loc)
-                  colorFormats.p(nodeName.toLowerCase(), loc)
-                  return
-                }
-
-                // Or it can be a named color
-                if (namedColors.has(nodeName)) {
-                  let stringified = stringifyNode(valueNode)
-                  colors.push(stringified, property, loc)
-                  colorFormats.p('named', loc)
-                  return
-                }
-
-                // Or it can be a system color
-                if (systemColors.has(nodeName)) {
-                  let stringified = stringifyNode(valueNode)
-                  colors.push(stringified, property, loc)
-                  colorFormats.p('system', loc)
-                  return
-                }
-                return this.skip
-              }
-              case Func: {
-                // Don't walk var() multiple times
-                if (strEquals('var', nodeName)) {
-                  return this.skip
-                }
-
-                // rgb(a), hsl(a), color(), hwb(), lch(), lab(), oklab(), oklch()
-                if (colorFunctions.has(nodeName)) {
-                  colors.push(stringifyNode(valueNode), property, valueNode.loc)
-                  colorFormats.p(nodeName.toLowerCase(), valueNode.loc)
-                  return
-                }
-
-                if (endsWith('gradient', nodeName)) {
-                  gradients.p(stringifyNode(valueNode), valueNode.loc)
-                  return
-                }
-                // No this.skip here intentionally,
-                // otherwise we'll miss colors in linear-gradient() etc.
-              }
-            }
-          })
-          break
-        }
-        case Declaration: {
-          // Do not process Declarations in atRule preludes
-          // because we will handle them manually
-          if (this.atrulePrelude !== null) {
-            return this.skip
-          }
-
-          totalDeclarations++
-          let complexity = 1
-
-          uniqueDeclarations.add(stringifyNode(node))
-          declarationNesting.push(nestingDepth - 1)
-          uniqueDeclarationNesting.p(nestingDepth - 1, node.loc)
-
-          if (node.important === true) {
-            importantDeclarations++
-            complexity++
-
-            if (this.atrule && endsWith('keyframes', this.atrule.name)) {
-              importantsInKeyframes++
-              complexity++
-            }
-          }
-
-          declarationComplexities.push(complexity)
-
-          let { property, loc: { start } } = node
-          let propertyLoc = {
-            start: {
-              line: start.line,
-              column: start.column,
-              offset: start.offset
-            },
-            end: {
-              offset: start.offset + property.length
-            }
-          }
-
-          properties.p(property, propertyLoc)
-
-          if (hasVendorPrefix(property)) {
-            propertyVendorPrefixes.p(property, propertyLoc)
-            propertyComplexities.push(2)
-          } else if (isHack(property)) {
-            propertyHacks.p(property, propertyLoc)
-            propertyComplexities.push(2)
-          } else if (isCustom(property)) {
-            customProperties.p(property, propertyLoc)
-            propertyComplexities.push(node.important ? 3 : 2)
-
-            if (node.important === true) {
-              importantCustomProperties.p(property, propertyLoc)
-            }
-          } else {
-            propertyComplexities.push(1)
-          }
-
-          break
-        }
-      }
-
-      if (node.type === Rule || node.type === Atrule) {
-        nestingDepth++
-      }
-    },
-    leave(node) {
-      if (node.type === Rule || node.type === Atrule) {
-        nestingDepth--
-      }
-    }
-  })
-
-  let totalUniqueDeclarations = uniqueDeclarations.size
-
-  let totalSelectors = selectorComplexities.size()
-  let specificitiesA = specificityA.aggregate()
-  let specificitiesB = specificityB.aggregate()
-  let specificitiesC = specificityC.aggregate()
-  let totalUniqueSelectors = uniqueSelectors.size
-  let assign = Object.assign
-  let cssLen = css.length
-  let fontFacesCount = fontfaces.length
-  let atRuleComplexity = atRuleComplexities.aggregate()
-  let selectorComplexity = selectorComplexities.aggregate()
-  let declarationComplexity = declarationComplexities.aggregate()
-  let propertyComplexity = propertyComplexities.aggregate()
-  let valueComplexity = valueComplexities.aggregate()
-  let atruleCount = atrules.c()
-
-  return {
-    stylesheet: {
-      sourceLinesOfCode: atruleCount.total + totalSelectors + totalDeclarations + keyframeSelectors.size(),
-      linesOfCode,
-      size: cssLen,
-      complexity: atRuleComplexity.sum + selectorComplexity.sum + declarationComplexity.sum + propertyComplexity.sum + valueComplexity.sum,
-      comments: {
-        total: totalComments,
-        size: commentsSize,
-      },
-      embeddedContent: {
-        size: {
-          total: embedSize,
-          ratio: ratio(embedSize, cssLen),
-        },
-        types: {
-          total: embedTypes.total,
-          totalUnique: embedTypes.unique.size,
-          uniquenessRatio: ratio(embedTypes.unique.size, embedTypes.total),
-          unique: Object.fromEntries(embedTypes.unique),
-        },
-      },
-    },
-    atrules: assign(
-      atruleCount,
-      {
-        fontface: assign({
-          total: fontFacesCount,
-          totalUnique: fontFacesCount,
-          unique: fontfaces,
-          uniquenessRatio: fontFacesCount === 0 ? 0 : 1,
-        }, useLocations ? {
-          uniqueWithLocations: fontfaces_with_loc.c().uniqueWithLocations,
-        } : {}),
-        import: imports.c(),
-        media: assign(
-          medias.c(),
-          {
-            browserhacks: mediaBrowserhacks.c(),
-            features: mediaFeatures.c(),
-          }
-        ),
-        charset: charsets.c(),
-        supports: assign(
-          supports.c(),
-          {
-            browserhacks: supportsBrowserhacks.c(),
-          },
-        ),
-        keyframes: assign(
-          keyframes.c(), {
-          prefixed: assign(
-            prefixedKeyframes.c(), {
-            ratio: ratio(prefixedKeyframes.size(), keyframes.size())
-          }),
-        }),
-        container: assign(
-          containers.c(),
-          {
-            names: containerNames.c(),
-          }
-        ),
-        layer: layers.c(),
-        property: registeredProperties.c(),
-        complexity: atRuleComplexity,
-        nesting: assign(
-          atruleNesting.aggregate(),
-          {
-            items: atruleNesting.toArray(),
-          },
-          uniqueAtruleNesting.c(),
-        ),
-      }
-    ),
-    rules: {
-      total: totalRules,
-      empty: {
-        total: emptyRules,
-        ratio: ratio(emptyRules, totalRules)
-      },
-      sizes: assign(
-        ruleSizes.aggregate(),
-        {
-          items: ruleSizes.toArray(),
-        },
-        uniqueRuleSize.c(),
-      ),
-      nesting: assign(
-        ruleNesting.aggregate(),
-        {
-          items: ruleNesting.toArray(),
-        },
-        uniqueRuleNesting.c(),
-      ),
-      selectors: assign(
-        selectorsPerRule.aggregate(),
-        {
-          items: selectorsPerRule.toArray(),
-        },
-        uniqueSelectorsPerRule.c(),
-      ),
-      declarations: assign(
-        declarationsPerRule.aggregate(),
-        {
-          items: declarationsPerRule.toArray(),
-        },
-        uniqueDeclarationsPerRule.c(),
-      ),
-    },
-    selectors: {
-      total: totalSelectors,
-      totalUnique: totalUniqueSelectors,
-      uniquenessRatio: ratio(totalUniqueSelectors, totalSelectors),
-      specificity: assign(
-        {
-          /** @type Specificity */
-          min: minSpecificity === undefined ? [0, 0, 0] : minSpecificity,
-          /** @type Specificity */
-          max: maxSpecificity === undefined ? [0, 0, 0] : maxSpecificity,
-          /** @type Specificity */
-          sum: [specificitiesA.sum, specificitiesB.sum, specificitiesC.sum],
-          /** @type Specificity */
-          mean: [specificitiesA.mean, specificitiesB.mean, specificitiesC.mean],
-          /** @type Specificity */
-          mode: [specificitiesA.mode, specificitiesB.mode, specificitiesC.mode],
-          /** @type Specificity */
-          items: specificities,
-        },
-        uniqueSpecificities.c(),
-      ),
-      complexity: assign(
-        selectorComplexity,
-        uniqueSelectorComplexities.c(),
-        {
-          items: selectorComplexities.toArray(),
-        }
-      ),
-      nesting: assign(
-        selectorNesting.aggregate(),
-        {
-          items: selectorNesting.toArray(),
-        },
-        uniqueSelectorNesting.c(),
-      ),
-      id: assign(
-        ids.c(), {
-        ratio: ratio(ids.size(), totalSelectors),
-      }),
-      pseudoClasses: pseudoClasses.c(),
-      accessibility: assign(
-        a11y.c(), {
-        ratio: ratio(a11y.size(), totalSelectors),
-      }),
-      keyframes: keyframeSelectors.c(),
-      prefixed: assign(
-        prefixedSelectors.c(),
-        {
-          ratio: ratio(prefixedSelectors.size(), totalSelectors),
-        },
-      ),
-      combinators: combinators.c(),
-    },
-    declarations: {
-      total: totalDeclarations,
-      totalUnique: totalUniqueDeclarations,
-      uniquenessRatio: ratio(totalUniqueDeclarations, totalDeclarations),
-      importants: {
-        total: importantDeclarations,
-        ratio: ratio(importantDeclarations, totalDeclarations),
-        inKeyframes: {
-          total: importantsInKeyframes,
-          ratio: ratio(importantsInKeyframes, importantDeclarations),
-        },
-      },
-      complexity: declarationComplexity,
-      nesting: assign(
-        declarationNesting.aggregate(),
-        {
-          items: declarationNesting.toArray(),
-        },
-        uniqueDeclarationNesting.c(),
-      ),
-    },
-    properties: assign(
-      properties.c(),
-      {
-        prefixed: assign(
-          propertyVendorPrefixes.c(),
-          {
-            ratio: ratio(propertyVendorPrefixes.size(), properties.size()),
-          },
-        ),
-        custom: assign(
-          customProperties.c(),
-          {
-            ratio: ratio(customProperties.size(), properties.size()),
-            importants: assign(
-              importantCustomProperties.c(),
-              {
-                ratio: ratio(importantCustomProperties.size(), customProperties.size()),
-              }
-            ),
-          },
-        ),
-        browserhacks: assign(
-          propertyHacks.c(), {
-          ratio: ratio(propertyHacks.size(), properties.size()),
-        }),
-        complexity: propertyComplexity,
-      }),
-    values: {
-      colors: assign(
-        colors.count(),
-        {
-          formats: colorFormats.c(),
-        },
-      ),
-      gradients: gradients.c(),
-      fontFamilies: fontFamilies.c(),
-      fontSizes: fontSizes.c(),
-      lineHeights: lineHeights.c(),
-      zindexes: zindex.c(),
-      textShadows: textShadows.c(),
-      boxShadows: boxShadows.c(),
-      borderRadiuses: borderRadiuses.count(),
-      animations: {
-        durations: durations.c(),
-        timingFunctions: timingFunctions.c(),
-      },
-      prefixes: vendorPrefixedValues.c(),
-      browserhacks: valueBrowserhacks.c(),
-      units: units.count(),
-      complexity: valueComplexity,
-      keywords: valueKeywords.c(),
-      resets: resets.c(),
-    },
-    __meta__: {
-      parseTime: startAnalysis - startParse,
-      analyzeTime: Date.now() - startAnalysis,
-      total: Date.now() - start
-    }
-  }
-}
-
-/**
- * Compare specificity A to Specificity B
- * @param {Specificity} a - Specificity A
- * @param {Specificity} b - Specificity B
- * @returns {number} sortIndex - 0 when a==b, 1 when a<b, -1 when a>b
- */
-export function compareSpecificity(a, b) {
-  if (a[0] === b[0]) {
-    if (a[1] === b[1]) {
-      return b[2] - a[2]
-    }
-
-    return b[1] - a[1]
-  }
-
-  return b[0] - a[0]
-}
-
-export {
-  getComplexity as selectorComplexity,
-  isPrefixed as isSelectorPrefixed,
-  isAccessibility as isAccessibilitySelector,
-} from './selectors/utils.js'
-
-export {
-  isSupportsBrowserhack,
-  isMediaBrowserhack
-} from './atrules/atrules.js'
-
-export {
-  isHack as isPropertyHack,
-} from './properties/property-utils.js'
-
-export {
-  isValuePrefixed
-} from './values/vendor-prefix.js'
-
-export {
-  colorFunctions,
-  colorKeywords,
-  namedColors,
-  systemColors,
-} from './values/colors.js'
-
-export { keywords as cssKeywords } from './values/values.js'
-
-export { hasVendorPrefix } from './vendor-prefix.js'
-
-export { KeywordSet } from './keyword-set.js'
diff --git a/src/index.test.js b/src/index.test.js
deleted file mode 100644
index 814301c5..00000000
--- a/src/index.test.js
+++ /dev/null
@@ -1,616 +0,0 @@
-import { suite } from "uvu"
-import * as assert from "uvu/assert"
-import {
-  analyze,
-  compareSpecificity,
-  selectorComplexity,
-  isAccessibilitySelector,
-  isSelectorPrefixed,
-  isMediaBrowserhack,
-  isSupportsBrowserhack,
-  isPropertyHack,
-  isValuePrefixed,
-  hasVendorPrefix,
-  cssKeywords,
-  KeywordSet,
-  // Color exports
-  namedColors,
-  systemColors,
-  colorFunctions,
-  colorKeywords,
-} from "./index.js"
-
-const Api = suite("Public API")
-
-Api("exposes the 'analyze' method", () => {
-  assert.is(typeof analyze, "function")
-})
-
-Api('exposes the "compareSpecificity" method', () => {
-  assert.is(typeof compareSpecificity, "function")
-})
-
-Api('exposes the "selectorComplexity" method', () => {
-  assert.is(typeof selectorComplexity, "function")
-})
-
-Api('exposes the "isSelectorPrefixed" method', () => {
-  assert.is(typeof isSelectorPrefixed, "function")
-})
-
-Api('exposes the "isAccessibilitySelector" method', () => {
-  assert.is(typeof isAccessibilitySelector, "function")
-})
-
-Api('exposes the "isMediaBrowserhack" method', () => {
-  assert.is(typeof isMediaBrowserhack, "function")
-})
-
-Api('exposes the "isSupportsBrowserhack" method', () => {
-  assert.is(typeof isSupportsBrowserhack, "function")
-})
-
-Api('exposes the "isPropertyHack" method', () => {
-  assert.is(typeof isPropertyHack, "function")
-})
-
-Api('exposes the "isValuePrefixed" method', () => {
-  assert.is(typeof isValuePrefixed, "function")
-})
-
-Api('exposes the "hasVendorPrefix" method', () => {
-  assert.is(typeof hasVendorPrefix, "function")
-})
-
-Api('exposes the namedColors KeywordSet', () => {
-  assert.ok(namedColors.has('Red'))
-})
-
-Api('exposes the systemColors KeywordSet', () => {
-  assert.ok(systemColors.has('LinkText'))
-})
-
-Api('exposes the colorFunctions KeywordSet', () => {
-  assert.ok(colorFunctions.has('okLAB'))
-})
-
-Api('exposes the colorKeywords KeywordSet', () => {
-  assert.ok(colorKeywords.has('TRANSPARENT'))
-})
-
-Api('exposes CSS keywords KeywordSet', () => {
-  assert.ok(cssKeywords.has('Auto'))
-  assert.ok(cssKeywords.has('inherit'))
-})
-
-Api('exposes the KeywordSet class', () => {
-  assert.is(typeof KeywordSet, 'function')
-  assert.is((new KeywordSet()).constructor.name, 'KeywordSet')
-})
-
-Api("does not break on CSS Syntax Errors", () => {
-  assert.not.throws(() => analyze("test, {}"))
-  assert.not.throws(() => analyze("test { color red }"))
-})
-
-Api("handles empty input gracefully", () => {
-  const actual = analyze("")
-  delete actual.__meta__
-  const expected = {
-    stylesheet: {
-      sourceLinesOfCode: 0,
-      linesOfCode: 1,
-      size: 0,
-      comments: {
-        total: 0,
-        size: 0,
-      },
-      embeddedContent: {
-        size: {
-          total: 0,
-          ratio: 0,
-        },
-        types: {
-          total: 0,
-          totalUnique: 0,
-          uniquenessRatio: 0,
-          unique: {},
-        },
-      },
-      complexity: 0,
-    },
-    atrules: {
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-      fontface: {
-        total: 0,
-        totalUnique: 0,
-        unique: [],
-        uniquenessRatio: 0,
-      },
-      import: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-      media: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-        browserhacks: {
-          total: 0,
-          totalUnique: 0,
-          unique: {},
-          uniquenessRatio: 0,
-        },
-        features: {
-          total: 0,
-          totalUnique: 0,
-          unique: {},
-          uniquenessRatio: 0,
-        },
-      },
-      charset: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-      supports: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-        browserhacks: {
-          total: 0,
-          totalUnique: 0,
-          unique: {},
-          uniquenessRatio: 0,
-        },
-      },
-      keyframes: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-        prefixed: {
-          total: 0,
-          totalUnique: 0,
-          unique: {},
-          uniquenessRatio: 0,
-          ratio: 0,
-        },
-      },
-      container: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-        names: {
-          total: 0,
-          totalUnique: 0,
-          unique: {},
-          uniquenessRatio: 0,
-        },
-      },
-      layer: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-      property: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-      complexity: {
-        min: 0,
-        max: 0,
-        mean: 0,
-        mode: 0,
-        range: 0,
-        sum: 0,
-      },
-      nesting: {
-        min: 0,
-        max: 0,
-        mean: 0,
-        mode: 0,
-        range: 0,
-        sum: 0,
-        items: [],
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      }
-    },
-    rules: {
-      total: 0,
-      empty: {
-        total: 0,
-        ratio: 0,
-      },
-      sizes: {
-        min: 0,
-        max: 0,
-        mean: 0,
-        mode: 0,
-        range: 0,
-        sum: 0,
-        items: [],
-        unique: {},
-        total: 0,
-        totalUnique: 0,
-        uniquenessRatio: 0,
-      },
-      nesting: {
-        min: 0,
-        max: 0,
-        mean: 0,
-        mode: 0,
-        range: 0,
-        sum: 0,
-        items: [],
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-      selectors: {
-        min: 0,
-        max: 0,
-        mean: 0,
-        mode: 0,
-        range: 0,
-        sum: 0,
-        items: [],
-        unique: {},
-        total: 0,
-        totalUnique: 0,
-        uniquenessRatio: 0,
-      },
-      declarations: {
-        min: 0,
-        max: 0,
-        mean: 0,
-        mode: 0,
-        range: 0,
-        sum: 0,
-        items: [],
-        unique: {},
-        total: 0,
-        totalUnique: 0,
-        uniquenessRatio: 0,
-      },
-    },
-    selectors: {
-      total: 0,
-      totalUnique: 0,
-      uniquenessRatio: 0,
-      specificity: {
-        min: [0, 0, 0],
-        max: [0, 0, 0],
-        sum: [0, 0, 0],
-        mean: [0, 0, 0],
-        mode: [0, 0, 0],
-        items: [],
-        unique: {},
-        total: 0,
-        totalUnique: 0,
-        uniquenessRatio: 0,
-      },
-      complexity: {
-        min: 0,
-        max: 0,
-        mean: 0,
-        mode: 0,
-        range: 0,
-        sum: 0,
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-        items: [],
-      },
-      nesting: {
-        min: 0,
-        max: 0,
-        mean: 0,
-        mode: 0,
-        range: 0,
-        sum: 0,
-        items: [],
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-      id: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-        ratio: 0,
-      },
-      pseudoClasses: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-      accessibility: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-        ratio: 0,
-      },
-      keyframes: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-      prefixed: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-        ratio: 0,
-      },
-      combinators: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-    },
-    declarations: {
-      total: 0,
-      totalUnique: 0,
-      uniquenessRatio: 0,
-      importants: {
-        total: 0,
-        ratio: 0,
-        inKeyframes: {
-          total: 0,
-          ratio: 0,
-        },
-      },
-      complexity: {
-        min: 0,
-        max: 0,
-        mean: 0,
-        mode: 0,
-        range: 0,
-        sum: 0,
-      },
-      nesting: {
-        min: 0,
-        max: 0,
-        mean: 0,
-        mode: 0,
-        range: 0,
-        sum: 0,
-        items: [],
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      }
-    },
-    properties: {
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-      prefixed: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-        ratio: 0,
-      },
-      custom: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-        ratio: 0,
-        importants: {
-          total: 0,
-          totalUnique: 0,
-          unique: {},
-          uniquenessRatio: 0,
-          ratio: 0,
-        },
-      },
-      browserhacks: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-        ratio: 0,
-      },
-      complexity: {
-        min: 0,
-        max: 0,
-        mean: 0,
-        mode: 0,
-        range: 0,
-        sum: 0,
-      },
-    },
-    values: {
-      colors: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-        itemsPerContext: {},
-        formats: {
-          total: 0,
-          totalUnique: 0,
-          unique: {},
-          uniquenessRatio: 0,
-        },
-      },
-      gradients: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-      fontFamilies: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-      fontSizes: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-      lineHeights: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-      zindexes: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-      textShadows: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-      boxShadows: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-      borderRadiuses: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        itemsPerContext: {},
-        uniquenessRatio: 0,
-      },
-      animations: {
-        durations: {
-          total: 0,
-          totalUnique: 0,
-          unique: {},
-          uniquenessRatio: 0,
-        },
-        timingFunctions: {
-          total: 0,
-          totalUnique: 0,
-          unique: {},
-          uniquenessRatio: 0,
-        },
-      },
-      prefixes: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-      browserhacks: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-      units: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-        itemsPerContext: {},
-      },
-      complexity: {
-        min: 0,
-        max: 0,
-        mean: 0,
-        mode: 0,
-        range: 0,
-        sum: 0,
-      },
-      keywords: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-      resets: {
-        total: 0,
-        totalUnique: 0,
-        unique: {},
-        uniquenessRatio: 0,
-      },
-    },
-  }
-
-  assert.equal(actual, expected)
-})
-
-Api("has metadata", () => {
-  const fixture = Array.from({ length: 100 })
-    .map(
-      (_) => `
-    html {
-      font: 1em/1 sans-serif;
-      color: rgb(0 0 0 / 0.5);
-    }
-
-    @media screen {
-      @supports (display: grid) {
-        test::after :where(test) :is(done) {
-          display: grid;
-          color: #f00;
-        }
-      }
-    }
-  `
-    )
-    .join("")
-
-  const result = analyze(fixture)
-  const actual = result.__meta__
-
-  assert.type(actual.parseTime, "number")
-  assert.ok(
-    actual.parseTime > 0,
-    `expected parseTime to be bigger than 0, got ${actual.parseTime}`
-  )
-
-  assert.type(actual.analyzeTime, "number")
-  assert.ok(
-    actual.analyzeTime > 0,
-    `expected analyzeTime to be bigger than 0, got ${actual.parseTime}`
-  )
-
-  assert.type(actual.total, "number")
-  assert.ok(
-    actual.total > 0,
-    `expected total time to be bigger than 0, got ${actual.parseTime}`
-  )
-})
-
-Api.run()
diff --git a/src/index.test.ts b/src/index.test.ts
new file mode 100644
index 00000000..154f1bdf
--- /dev/null
+++ b/src/index.test.ts
@@ -0,0 +1,603 @@
+import { test, expect } from 'vitest'
+import {
+	analyze,
+	compareSpecificity,
+	selectorComplexity,
+	isAccessibilitySelector,
+	isSelectorPrefixed,
+	isMediaBrowserhack,
+	isSupportsBrowserhack,
+	isPropertyHack,
+	isValuePrefixed,
+	hasVendorPrefix,
+	cssKeywords,
+	KeywordSet,
+	// Color exports
+	namedColors,
+	systemColors,
+	colorFunctions,
+	colorKeywords,
+} from './index.js'
+
+test("exposes the 'analyze' method", () => {
+	expect(typeof analyze).toBe('function')
+})
+
+test('exposes the "compareSpecificity" method', () => {
+	expect(typeof compareSpecificity).toBe('function')
+})
+
+test('exposes the "selectorComplexity" method', () => {
+	expect(typeof selectorComplexity).toBe('function')
+})
+
+test('exposes the "isSelectorPrefixed" method', () => {
+	expect(typeof isSelectorPrefixed).toBe('function')
+})
+
+test('exposes the "isAccessibilitySelector" method', () => {
+	expect(typeof isAccessibilitySelector).toBe('function')
+})
+
+test('exposes the "isMediaBrowserhack" method', () => {
+	expect(typeof isMediaBrowserhack).toBe('function')
+})
+
+test('exposes the "isSupportsBrowserhack" method', () => {
+	expect(typeof isSupportsBrowserhack).toBe('function')
+})
+
+test('exposes the "isPropertyHack" method', () => {
+	expect(typeof isPropertyHack).toBe('function')
+})
+
+test('exposes the "isValuePrefixed" method', () => {
+	expect(typeof isValuePrefixed).toBe('function')
+})
+
+test('exposes the "hasVendorPrefix" method', () => {
+	expect(typeof hasVendorPrefix).toBe('function')
+})
+
+test('exposes the namedColors KeywordSet', () => {
+	expect(namedColors.has('Red')).toBeTruthy()
+})
+
+test('exposes the systemColors KeywordSet', () => {
+	expect(systemColors.has('LinkText')).toBeTruthy()
+})
+
+test('exposes the colorFunctions KeywordSet', () => {
+	expect(colorFunctions.has('okLAB')).toBeTruthy()
+})
+
+test('exposes the colorKeywords KeywordSet', () => {
+	expect(colorKeywords.has('TRANSPARENT')).toBeTruthy()
+})
+
+test('exposes CSS keywords KeywordSet', () => {
+	expect(cssKeywords.has('Auto')).toBeTruthy()
+	expect(cssKeywords.has('inherit')).toBeTruthy()
+})
+
+test('exposes the KeywordSet class', () => {
+	expect(typeof KeywordSet).toBe('function')
+	expect(new KeywordSet([]).constructor.name).toBe('KeywordSet')
+})
+
+test('does not break on CSS Syntax Errors', () => {
+	expect(() => analyze('test, {}')).not.toThrow()
+	expect(() => analyze('test { color red }')).not.toThrow()
+})
+
+test('handles empty input gracefully', () => {
+	const actual = analyze('')
+	// @ts-expect-error Just for testing purposes
+	delete actual.__meta__
+	const expected = {
+		stylesheet: {
+			sourceLinesOfCode: 0,
+			linesOfCode: 1,
+			size: 0,
+			comments: {
+				total: 0,
+				size: 0,
+			},
+			embeddedContent: {
+				size: {
+					total: 0,
+					ratio: 0,
+				},
+				types: {
+					total: 0,
+					totalUnique: 0,
+					uniquenessRatio: 0,
+					unique: {},
+				},
+			},
+			complexity: 0,
+		},
+		atrules: {
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+			fontface: {
+				total: 0,
+				totalUnique: 0,
+				unique: [],
+				uniquenessRatio: 0,
+			},
+			import: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+			media: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+				browserhacks: {
+					total: 0,
+					totalUnique: 0,
+					unique: {},
+					uniquenessRatio: 0,
+				},
+				features: {
+					total: 0,
+					totalUnique: 0,
+					unique: {},
+					uniquenessRatio: 0,
+				},
+			},
+			charset: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+			supports: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+				browserhacks: {
+					total: 0,
+					totalUnique: 0,
+					unique: {},
+					uniquenessRatio: 0,
+				},
+			},
+			keyframes: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+				prefixed: {
+					total: 0,
+					totalUnique: 0,
+					unique: {},
+					uniquenessRatio: 0,
+					ratio: 0,
+				},
+			},
+			container: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+				names: {
+					total: 0,
+					totalUnique: 0,
+					unique: {},
+					uniquenessRatio: 0,
+				},
+			},
+			layer: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+			property: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+			complexity: {
+				min: 0,
+				max: 0,
+				mean: 0,
+				mode: 0,
+				range: 0,
+				sum: 0,
+			},
+			nesting: {
+				min: 0,
+				max: 0,
+				mean: 0,
+				mode: 0,
+				range: 0,
+				sum: 0,
+				items: [],
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+		},
+		rules: {
+			total: 0,
+			empty: {
+				total: 0,
+				ratio: 0,
+			},
+			sizes: {
+				min: 0,
+				max: 0,
+				mean: 0,
+				mode: 0,
+				range: 0,
+				sum: 0,
+				items: [],
+				unique: {},
+				total: 0,
+				totalUnique: 0,
+				uniquenessRatio: 0,
+			},
+			nesting: {
+				min: 0,
+				max: 0,
+				mean: 0,
+				mode: 0,
+				range: 0,
+				sum: 0,
+				items: [],
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+			selectors: {
+				min: 0,
+				max: 0,
+				mean: 0,
+				mode: 0,
+				range: 0,
+				sum: 0,
+				items: [],
+				unique: {},
+				total: 0,
+				totalUnique: 0,
+				uniquenessRatio: 0,
+			},
+			declarations: {
+				min: 0,
+				max: 0,
+				mean: 0,
+				mode: 0,
+				range: 0,
+				sum: 0,
+				items: [],
+				unique: {},
+				total: 0,
+				totalUnique: 0,
+				uniquenessRatio: 0,
+			},
+		},
+		selectors: {
+			total: 0,
+			totalUnique: 0,
+			uniquenessRatio: 0,
+			specificity: {
+				min: [0, 0, 0],
+				max: [0, 0, 0],
+				sum: [0, 0, 0],
+				mean: [0, 0, 0],
+				mode: [0, 0, 0],
+				items: [],
+				unique: {},
+				total: 0,
+				totalUnique: 0,
+				uniquenessRatio: 0,
+			},
+			complexity: {
+				min: 0,
+				max: 0,
+				mean: 0,
+				mode: 0,
+				range: 0,
+				sum: 0,
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+				items: [],
+			},
+			nesting: {
+				min: 0,
+				max: 0,
+				mean: 0,
+				mode: 0,
+				range: 0,
+				sum: 0,
+				items: [],
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+			id: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+				ratio: 0,
+			},
+			pseudoClasses: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+			accessibility: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+				ratio: 0,
+			},
+			keyframes: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+			prefixed: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+				ratio: 0,
+			},
+			combinators: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+		},
+		declarations: {
+			total: 0,
+			totalUnique: 0,
+			uniquenessRatio: 0,
+			importants: {
+				total: 0,
+				ratio: 0,
+				inKeyframes: {
+					total: 0,
+					ratio: 0,
+				},
+			},
+			complexity: {
+				min: 0,
+				max: 0,
+				mean: 0,
+				mode: 0,
+				range: 0,
+				sum: 0,
+			},
+			nesting: {
+				min: 0,
+				max: 0,
+				mean: 0,
+				mode: 0,
+				range: 0,
+				sum: 0,
+				items: [],
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+		},
+		properties: {
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+			prefixed: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+				ratio: 0,
+			},
+			custom: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+				ratio: 0,
+				importants: {
+					total: 0,
+					totalUnique: 0,
+					unique: {},
+					uniquenessRatio: 0,
+					ratio: 0,
+				},
+			},
+			browserhacks: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+				ratio: 0,
+			},
+			complexity: {
+				min: 0,
+				max: 0,
+				mean: 0,
+				mode: 0,
+				range: 0,
+				sum: 0,
+			},
+		},
+		values: {
+			colors: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+				itemsPerContext: {},
+				formats: {
+					total: 0,
+					totalUnique: 0,
+					unique: {},
+					uniquenessRatio: 0,
+				},
+			},
+			gradients: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+			fontFamilies: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+			fontSizes: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+			lineHeights: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+			zindexes: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+			textShadows: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+			boxShadows: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+			borderRadiuses: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				itemsPerContext: {},
+				uniquenessRatio: 0,
+			},
+			animations: {
+				durations: {
+					total: 0,
+					totalUnique: 0,
+					unique: {},
+					uniquenessRatio: 0,
+				},
+				timingFunctions: {
+					total: 0,
+					totalUnique: 0,
+					unique: {},
+					uniquenessRatio: 0,
+				},
+			},
+			prefixes: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+			browserhacks: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+			units: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+				itemsPerContext: {},
+			},
+			complexity: {
+				min: 0,
+				max: 0,
+				mean: 0,
+				mode: 0,
+				range: 0,
+				sum: 0,
+			},
+			keywords: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+			resets: {
+				total: 0,
+				totalUnique: 0,
+				unique: {},
+				uniquenessRatio: 0,
+			},
+		},
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('has metadata', () => {
+	const fixture = Array.from({ length: 100 })
+		.map(
+			(_) => `
+    html {
+      font: 1em/1 sans-serif;
+      color: rgb(0 0 0 / 0.5);
+    }
+
+    @media screen {
+      @supports (display: grid) {
+        test::after :where(test) :is(done) {
+          display: grid;
+          color: #f00;
+        }
+      }
+    }
+  `,
+		)
+		.join('')
+
+	const result = analyze(fixture)
+	const actual = result.__meta__
+
+	expect(typeof actual.parseTime).toBe('number')
+	expect(actual.parseTime).toBeGreaterThan(0)
+
+	expect(typeof actual.analyzeTime).toBe('number')
+	expect(actual.analyzeTime).toBeGreaterThan(0)
+
+	expect(typeof actual.total).toBe('number')
+	expect(actual.total).toBeGreaterThan(0)
+})
diff --git a/src/index.ts b/src/index.ts
new file mode 100644
index 00000000..4ec977f1
--- /dev/null
+++ b/src/index.ts
@@ -0,0 +1,1023 @@
+// @ts-expect-error types missing
+import parse from 'css-tree/parser'
+// @ts-expect-error types missing
+import walk from 'css-tree/walker'
+// @ts-expect-error types missing
+import { calculateForAST } from '@bramus/specificity/core'
+import { isSupportsBrowserhack, isMediaBrowserhack } from './atrules/atrules.js'
+import { getCombinators, getComplexity, isAccessibility, isPrefixed, hasPseudoClass } from './selectors/utils.js'
+import { colorFunctions, colorKeywords, namedColors, systemColors } from './values/colors.js'
+import { destructure, isSystemFont } from './values/destructure-font-shorthand.js'
+import { isValueKeyword, keywords, isValueReset } from './values/values.js'
+import { analyzeAnimation } from './values/animations.js'
+import { isValuePrefixed } from './values/vendor-prefix.js'
+import { ContextCollection } from './context-collection.js'
+import { Collection } from './collection.js'
+import { AggregateCollection } from './aggregate-collection.js'
+import { strEquals, startsWith, endsWith } from './string-utils.js'
+import { hasVendorPrefix } from './vendor-prefix.js'
+import { isCustom, isHack, isProperty } from './properties/property-utils.js'
+import { getEmbedType } from './stylesheet/stylesheet.js'
+import { isIe9Hack } from './values/browserhacks.js'
+import { basename } from './properties/property-utils.js'
+import { Atrule, Selector, Dimension, Url, Value, Hash, Rule, Identifier, Func, Operator } from './css-tree-node-types.js'
+import { KeywordSet } from './keyword-set.js'
+import type { CssNode, Declaration, SelectorList } from 'css-tree'
+
+type Specificity = [number, number, number]
+
+let border_radius_properties = new KeywordSet([
+	'border-radius',
+	'border-top-left-radius',
+	'border-top-right-radius',
+	'border-bottom-right-radius',
+	'border-bottom-left-radius',
+	'border-start-start-radius',
+	'border-start-end-radius',
+	'border-end-end-radius',
+	'border-end-start-radius',
+])
+
+function ratio(part: number, total: number): number {
+	if (total === 0) return 0
+	return part / total
+}
+
+let defaults = {
+	useLocations: false,
+}
+
+type Options = {
+	/** @description Use Locations (`{ 'item': [{ line, column, offset, length }] }`) instead of a regular count per occurrence (`{ 'item': 3 }`) */
+	useLocations?: boolean
+}
+
+export function analyze(css: string, options: Options = {}) {
+	let settings = Object.assign({}, defaults, options)
+	let useLocations = settings.useLocations === true
+	let start = Date.now()
+
+	/**
+	 * Recreate the authored CSS from a CSSTree node
+	 * @param {import('css-tree').CssNode} node - Node from CSSTree AST to stringify
+	 * @returns {string} str - The stringified node
+	 */
+	function stringifyNode(node: CssNode) {
+		return stringifyNodePlain(node).trim()
+	}
+
+	function stringifyNodePlain(node: CssNode) {
+		let loc = node.loc!
+		return css.substring(loc.start.offset, loc.end.offset)
+	}
+
+	// Stylesheet
+	let totalComments = 0
+	let commentsSize = 0
+	let embedSize = 0
+	let embedTypes = {
+		total: 0,
+		/** @type {Map<string, { size: number, count: number } & ({ uniqueWithLocations?: undefined } | ({ uniqueWithLocations: { offset: number, line: number, column: number, length: number }[] })) }>} */
+		unique: new Map(),
+	}
+
+	let startParse = Date.now()
+
+	let ast = parse(css, {
+		parseCustomProperty: true, // To find font-families, colors, etc.
+		positions: true, // So we can use stringifyNode()
+		onComment: function (comment: string) {
+			totalComments++
+			commentsSize += comment.length
+		},
+	})
+
+	let startAnalysis = Date.now()
+	let linesOfCode = ast.loc.end.line - ast.loc.start.line + 1
+
+	// Atrules
+	let atrules = new Collection(useLocations)
+	let atRuleComplexities = new AggregateCollection()
+	/** @type {Record<string, string>[]} */
+	let fontfaces: Record<string, string>[] = []
+	let fontfaces_with_loc = new Collection(useLocations)
+	let layers = new Collection(useLocations)
+	let imports = new Collection(useLocations)
+	let medias = new Collection(useLocations)
+	let mediaBrowserhacks = new Collection(useLocations)
+	let mediaFeatures = new Collection(useLocations)
+	let charsets = new Collection(useLocations)
+	let supports = new Collection(useLocations)
+	let supportsBrowserhacks = new Collection(useLocations)
+	let keyframes = new Collection(useLocations)
+	let prefixedKeyframes = new Collection(useLocations)
+	let containers = new Collection(useLocations)
+	let containerNames = new Collection(useLocations)
+	let registeredProperties = new Collection(useLocations)
+	let atruleNesting = new AggregateCollection()
+	let uniqueAtruleNesting = new Collection(useLocations)
+
+	// Rules
+	let totalRules = 0
+	let emptyRules = 0
+	let ruleSizes = new AggregateCollection()
+	let selectorsPerRule = new AggregateCollection()
+	let declarationsPerRule = new AggregateCollection()
+	let uniqueRuleSize = new Collection(useLocations)
+	let uniqueSelectorsPerRule = new Collection(useLocations)
+	let uniqueDeclarationsPerRule = new Collection(useLocations)
+	let ruleNesting = new AggregateCollection()
+	let uniqueRuleNesting = new Collection(useLocations)
+
+	// Selectors
+	let keyframeSelectors = new Collection(useLocations)
+	let uniqueSelectors = new Set()
+	let prefixedSelectors = new Collection(useLocations)
+	let maxSpecificity: Specificity | undefined
+	let minSpecificity: Specificity | undefined
+	let specificityA = new AggregateCollection()
+	let specificityB = new AggregateCollection()
+	let specificityC = new AggregateCollection()
+	let uniqueSpecificities = new Collection(useLocations)
+	let selectorComplexities = new AggregateCollection()
+	let uniqueSelectorComplexities = new Collection(useLocations)
+	let specificities: Specificity[] = []
+	let ids = new Collection(useLocations)
+	let a11y = new Collection(useLocations)
+	let pseudoClasses = new Collection(useLocations)
+	let combinators = new Collection(useLocations)
+	let selectorNesting = new AggregateCollection()
+	let uniqueSelectorNesting = new Collection(useLocations)
+
+	// Declarations
+	let uniqueDeclarations = new Set()
+	let totalDeclarations = 0
+	let declarationComplexities = new AggregateCollection()
+	let importantDeclarations = 0
+	let importantsInKeyframes = 0
+	let importantCustomProperties = new Collection(useLocations)
+	let declarationNesting = new AggregateCollection()
+	let uniqueDeclarationNesting = new Collection(useLocations)
+
+	// Properties
+	let properties = new Collection(useLocations)
+	let propertyHacks = new Collection(useLocations)
+	let propertyVendorPrefixes = new Collection(useLocations)
+	let customProperties = new Collection(useLocations)
+	let propertyComplexities = new AggregateCollection()
+
+	// Values
+	let valueComplexities = new AggregateCollection()
+	let vendorPrefixedValues = new Collection(useLocations)
+	let valueBrowserhacks = new Collection(useLocations)
+	let zindex = new Collection(useLocations)
+	let textShadows = new Collection(useLocations)
+	let boxShadows = new Collection(useLocations)
+	let fontFamilies = new Collection(useLocations)
+	let fontSizes = new Collection(useLocations)
+	let lineHeights = new Collection(useLocations)
+	let timingFunctions = new Collection(useLocations)
+	let durations = new Collection(useLocations)
+	let colors = new ContextCollection(useLocations)
+	let colorFormats = new Collection(useLocations)
+	let units = new ContextCollection(useLocations)
+	let gradients = new Collection(useLocations)
+	let valueKeywords = new Collection(useLocations)
+	let borderRadiuses = new ContextCollection(useLocations)
+	let resets = new Collection(useLocations)
+
+	let nestingDepth = 0
+
+	walk(ast, {
+		enter(node: CssNode) {
+			switch (node.type) {
+				case Atrule: {
+					atrules.p(node.name, node.loc!)
+					atruleNesting.push(nestingDepth)
+					uniqueAtruleNesting.p(nestingDepth, node.loc!)
+
+					let atRuleName = node.name
+
+					if (atRuleName === 'font-face') {
+						let descriptors = Object.create(null)
+
+						if (useLocations) {
+							fontfaces_with_loc.p(node.loc!.start.offset, node.loc!)
+						}
+
+						node.block?.children.forEach((descriptor) => {
+							// Ignore 'Raw' nodes in case of CSS syntax errors
+							if (descriptor.type === 'Declaration') {
+								descriptors[descriptor.property] = stringifyNode(descriptor.value)
+							}
+						})
+
+						fontfaces.push(descriptors)
+						atRuleComplexities.push(1)
+						break
+					}
+
+					let complexity = 1
+
+					// All the AtRules in here MUST have a prelude, so we can count their names
+					if (node.prelude !== null) {
+						let prelude = node.prelude
+						let preludeStr = prelude && stringifyNode(node.prelude)
+						let loc = prelude.loc!
+
+						if (atRuleName === 'media') {
+							medias.p(preludeStr, loc)
+							if (isMediaBrowserhack(prelude)) {
+								mediaBrowserhacks.p(preludeStr, loc)
+								complexity++
+							}
+						} else if (atRuleName === 'supports') {
+							supports.p(preludeStr, loc)
+							// TODO: analyze vendor prefixes in @supports
+							// TODO: analyze complexity of @supports 'declaration'
+							if (isSupportsBrowserhack(prelude)) {
+								supportsBrowserhacks.p(preludeStr, loc)
+								complexity++
+							}
+						} else if (endsWith('keyframes', atRuleName)) {
+							let name = '@' + atRuleName + ' ' + preludeStr
+							if (hasVendorPrefix(atRuleName)) {
+								prefixedKeyframes.p(name, loc)
+								complexity++
+							}
+							keyframes.p(name, loc!)
+						} else if (atRuleName === 'import') {
+							// @ts-expect-error Outdated css-tree types
+							walk(node, (prelude_node) => {
+								if (prelude_node.type === 'Condition' && prelude_node.kind === 'supports') {
+									let prelude = stringifyNode(prelude_node)
+
+									supports.p(prelude, prelude_node.loc!)
+									return walk.break
+								}
+							})
+							imports.p(preludeStr, loc)
+							// TODO: analyze complexity of media queries, layers and supports in @import
+							// see https://github.com/projectwallace/css-analyzer/issues/326
+						} else if (atRuleName === 'charset') {
+							charsets.p(preludeStr, loc)
+						} else if (atRuleName === 'container') {
+							containers.p(preludeStr, loc)
+
+							if (prelude.type === 'AtrulePrelude') {
+								if (prelude.children.first?.type === 'Identifier') {
+									let containerName = prelude.children.first.name
+									containerNames.p(containerName, loc)
+								}
+							}
+							// TODO: calculate complexity of container 'declaration'
+						} else if (atRuleName === 'property') {
+							registeredProperties.p(preludeStr, loc)
+							// TODO: add complexity for descriptors
+						}
+					} else {
+						if (atRuleName === 'layer') {
+							layers.p('<anonymous>', node.loc!)
+							complexity++
+						}
+					}
+					atRuleComplexities.push(complexity)
+					break
+				}
+				// @ts-expect-error Oudated css-tree types
+				case 'Layer': {
+					// @ts-expect-error Oudated css-tree types
+					if (node.name !== null) {
+						// @ts-expect-error Oudated css-tree types
+						layers.p(node.name, node.loc)
+					}
+					break
+				}
+				// @ts-expect-error Oudated css-tree types
+				case 'Feature': {
+					// @ts-expect-error Oudated css-tree types
+					mediaFeatures.p(node.name, node.loc)
+					break
+				}
+				case Rule: {
+					let prelude = node.prelude as SelectorList
+					let block = node.block
+
+					let preludeChildren = prelude.children
+					let blockChildren = block.children
+					let numSelectors = preludeChildren ? preludeChildren.size : 0
+					let numDeclarations = blockChildren ? blockChildren.size : 0
+
+					ruleSizes.push(numSelectors + numDeclarations)
+					uniqueRuleSize.p(numSelectors + numDeclarations, node.loc!)
+					selectorsPerRule.push(numSelectors)
+					uniqueSelectorsPerRule.p(numSelectors, prelude.loc!)
+					declarationsPerRule.push(numDeclarations)
+					uniqueDeclarationsPerRule.p(numDeclarations, block.loc!)
+					ruleNesting.push(nestingDepth)
+					uniqueRuleNesting.p(nestingDepth, node.loc!)
+
+					totalRules++
+
+					if (numDeclarations === 0) {
+						emptyRules++
+					}
+					break
+				}
+				case Selector: {
+					let selector = stringifyNode(node)
+
+					if (this.atrule && endsWith('keyframes', this.atrule.name)) {
+						keyframeSelectors.p(selector, node.loc!)
+						return this.skip
+					}
+
+					if (isAccessibility(node)) {
+						a11y.p(selector, node.loc!)
+					}
+
+					let pseudos = hasPseudoClass(node)
+					if (pseudos !== false) {
+						for (let pseudo of pseudos) {
+							pseudoClasses.p(pseudo, node.loc!)
+						}
+					}
+
+					let complexity = getComplexity(node)
+
+					if (isPrefixed(node)) {
+						prefixedSelectors.p(selector, node.loc!)
+					}
+
+					uniqueSelectors.add(selector)
+					selectorComplexities.push(complexity)
+					uniqueSelectorComplexities.p(complexity, node.loc!)
+					selectorNesting.push(nestingDepth - 1)
+					uniqueSelectorNesting.p(nestingDepth - 1, node.loc!)
+
+					// #region specificity
+					let specificity = calculateForAST(node).toArray()
+					let [sa, sb, sc] = specificity
+
+					uniqueSpecificities.p(specificity.toString(), node.loc!)
+
+					specificityA.push(sa)
+					specificityB.push(sb)
+					specificityC.push(sc)
+
+					if (maxSpecificity === undefined) {
+						maxSpecificity = specificity
+					}
+
+					if (minSpecificity === undefined) {
+						minSpecificity = specificity
+					}
+
+					if (minSpecificity !== undefined && compareSpecificity(minSpecificity, specificity) < 0) {
+						minSpecificity = specificity
+					}
+
+					if (maxSpecificity !== undefined && compareSpecificity(maxSpecificity, specificity) > 0) {
+						maxSpecificity = specificity
+					}
+
+					specificities.push(specificity)
+					// #endregion
+
+					if (sa > 0) {
+						ids.p(selector, node.loc!)
+					}
+
+					getCombinators(node, function onCombinator(combinator) {
+						combinators.p(combinator.name, combinator.loc)
+					})
+
+					// Avoid deeper walking of selectors to not mess with
+					// our specificity calculations in case of a selector
+					// with :where() or :is() that contain SelectorLists
+					// as children
+					return this.skip
+				}
+				case Dimension: {
+					if (!this.declaration) {
+						break
+					}
+
+					let unit = node.unit
+
+					if (endsWith('\\9', unit)) {
+						units.push(unit.substring(0, unit.length - 2), this.declaration.property, node.loc!)
+					} else {
+						units.push(unit, this.declaration.property, node.loc!)
+					}
+
+					return this.skip
+				}
+				case Url: {
+					if (startsWith('data:', node.value)) {
+						let embed = node.value
+						let size = embed.length
+						let type = getEmbedType(embed)
+
+						embedTypes.total++
+						embedSize += size
+
+						let loc = {
+							line: node.loc!.start.line,
+							column: node.loc!.start.column,
+							offset: node.loc!.start.offset,
+							length: node.loc!.end.offset - node.loc!.start.offset,
+						}
+
+						if (embedTypes.unique.has(type)) {
+							let item = embedTypes.unique.get(type)
+							item.count++
+							item.size += size
+							embedTypes.unique.set(type, item)
+							if (useLocations) {
+								item.uniqueWithLocations.push(loc)
+							}
+						} else {
+							let item = {
+								count: 1,
+								size,
+								uniqueWithLocations: useLocations ? [loc] : undefined,
+							}
+							embedTypes.unique.set(type, item)
+						}
+					}
+					break
+				}
+				case Value: {
+					let loc = node.loc!
+
+					if (isValueKeyword(node)) {
+						valueComplexities.push(1)
+						valueKeywords.p(stringifyNode(node), loc)
+						break
+					}
+
+					let declaration: Declaration = this.declaration
+					let { property, important } = declaration
+					let complexity = 1
+
+					// i.e. `background-image: -webkit-linear-gradient()`
+					if (isValuePrefixed(node)) {
+						vendorPrefixedValues.p(stringifyNode(node), loc)
+						complexity++
+					}
+
+					// i.e. `property: value !ie`
+					if (typeof important === 'string') {
+						valueBrowserhacks.p(stringifyNodePlain(node) + '!' + important, loc)
+						complexity++
+					}
+
+					// i.e. `property: value\9`
+					if (isIe9Hack(node)) {
+						valueBrowserhacks.p(stringifyNode(node), loc)
+						complexity++
+					}
+
+					let children = node.children
+
+					// TODO: should shorthands be counted towards complexity?
+					valueComplexities.push(complexity)
+
+					// Process properties first that don't have colors,
+					// so we can avoid further walking them;
+					if (
+						isProperty('margin', property) ||
+						isProperty('margin-block', property) ||
+						isProperty('margin-inline', property) ||
+						isProperty('margin-top', property) ||
+						isProperty('margin-right', property) ||
+						isProperty('margin-bottom', property) ||
+						isProperty('margin-left', property) ||
+						isProperty('padding', property) ||
+						isProperty('padding-block', property) ||
+						isProperty('padding-inline', property) ||
+						isProperty('padding-top', property) ||
+						isProperty('padding-right', property) ||
+						isProperty('padding-bottom', property) ||
+						isProperty('padding-left', property)
+					) {
+						if (isValueReset(node)) {
+							resets.p(property, declaration.loc!)
+						}
+					} else if (isProperty('z-index', property)) {
+						zindex.p(stringifyNode(node), loc)
+						return this.skip
+					} else if (isProperty('font', property)) {
+						if (isSystemFont(node)) return
+
+						let result = destructure(node, stringifyNode, function (item) {
+							if (item.type === 'keyword') {
+								valueKeywords.p(item.value, loc)
+							}
+						})
+
+						if (!result) {
+							return this.skip
+						}
+
+						let { font_size, line_height, font_family } = result
+						if (font_family) {
+							fontFamilies.p(font_family, loc)
+						}
+
+						if (font_size) {
+							fontSizes.p(font_size, loc)
+						}
+
+						if (line_height) {
+							lineHeights.p(line_height, loc)
+						}
+
+						break
+					} else if (isProperty('font-size', property)) {
+						if (!isSystemFont(node)) {
+							fontSizes.p(stringifyNode(node), loc)
+						}
+						break
+					} else if (isProperty('font-family', property)) {
+						if (!isSystemFont(node)) {
+							fontFamilies.p(stringifyNode(node), loc)
+						}
+						break
+					} else if (isProperty('line-height', property)) {
+						lineHeights.p(stringifyNode(node), loc)
+					} else if (isProperty('transition', property) || isProperty('animation', property)) {
+						analyzeAnimation(children, function (item: { type: string; value: CssNode }) {
+							if (item.type === 'fn') {
+								timingFunctions.p(stringifyNode(item.value), loc)
+							} else if (item.type === 'duration') {
+								durations.p(stringifyNode(item.value), loc)
+							} else if (item.type === 'keyword') {
+								valueKeywords.p(stringifyNode(item.value), loc)
+							}
+						})
+						break
+					} else if (isProperty('animation-duration', property) || isProperty('transition-duration', property)) {
+						if (children && children.size > 1) {
+							children.forEach((child) => {
+								if (child.type !== Operator) {
+									durations.p(stringifyNode(child), loc)
+								}
+							})
+						} else {
+							durations.p(stringifyNode(node), loc)
+						}
+						break
+					} else if (isProperty('transition-timing-function', property) || isProperty('animation-timing-function', property)) {
+						if (children && children.size > 1) {
+							children.forEach((child) => {
+								if (child.type !== Operator) {
+									timingFunctions.p(stringifyNode(child), loc)
+								}
+							})
+						} else {
+							timingFunctions.p(stringifyNode(node), loc)
+						}
+						break
+					} else if (isProperty('container-name', property)) {
+						containerNames.p(stringifyNode(node), loc)
+					} else if (isProperty('container', property)) {
+						// The first identifier is the container name
+						// Example: container: my-layout / inline-size;
+						if (children.first?.type === 'Identifier') {
+							containerNames.p(children.first.name, loc)
+						}
+					} else if (border_radius_properties.has(basename(property))) {
+						if (!isValueKeyword(node)) {
+							borderRadiuses.push(stringifyNode(node), property, loc)
+						}
+						break
+					} else if (isProperty('text-shadow', property)) {
+						if (!isValueKeyword(node)) {
+							textShadows.p(stringifyNode(node), loc)
+						}
+						// no break here: potentially contains colors
+					} else if (isProperty('box-shadow', property)) {
+						if (!isValueKeyword(node)) {
+							boxShadows.p(stringifyNode(node), loc)
+						}
+						// no break here: potentially contains colors
+					}
+
+					walk(node, function (valueNode: CssNode) {
+						// @ts-expect-error TODO: fix this
+						let nodeName = valueNode.name
+
+						switch (valueNode.type) {
+							case Hash: {
+								let hexLength = valueNode.value.length
+								if (endsWith('\\9', valueNode.value)) {
+									hexLength = hexLength - 2
+								}
+								colors.push('#' + valueNode.value, property, loc)
+								colorFormats.p(`hex` + hexLength, loc)
+
+								return walk.skip
+							}
+							case Identifier: {
+								if (keywords.has(nodeName)) {
+									valueKeywords.p(nodeName, loc)
+								}
+
+								// Bail out if it can't be a color name
+								// 20 === 'lightgoldenrodyellow'.length
+								// 3 === 'red'.length
+								let nodeLen = nodeName.length
+								if (nodeLen > 20 || nodeLen < 3) {
+									return walk.skip
+								}
+
+								// A keyword is most likely to be 'transparent' or 'currentColor'
+								if (colorKeywords.has(nodeName)) {
+									let stringified = stringifyNode(valueNode)
+									colors.push(stringified, property, loc)
+									colorFormats.p(nodeName.toLowerCase(), loc)
+									return
+								}
+
+								// Or it can be a named color
+								if (namedColors.has(nodeName)) {
+									let stringified = stringifyNode(valueNode)
+									colors.push(stringified, property, loc)
+									colorFormats.p('named', loc)
+									return
+								}
+
+								// Or it can be a system color
+								if (systemColors.has(nodeName)) {
+									let stringified = stringifyNode(valueNode)
+									colors.push(stringified, property, loc)
+									colorFormats.p('system', loc)
+									return
+								}
+								return walk.skip
+							}
+							case Func: {
+								// Don't walk var() multiple times
+								if (strEquals('var', nodeName)) {
+									return walk.skip
+								}
+
+								// rgb(a), hsl(a), color(), hwb(), lch(), lab(), oklab(), oklch()
+								if (colorFunctions.has(nodeName)) {
+									colors.push(stringifyNode(valueNode), property, valueNode.loc!)
+									colorFormats.p(nodeName.toLowerCase(), valueNode.loc!)
+									return
+								}
+
+								if (endsWith('gradient', nodeName)) {
+									gradients.p(stringifyNode(valueNode), valueNode.loc!)
+									return
+								}
+								// No walk.skip here intentionally,
+								// otherwise we'll miss colors in linear-gradient() etc.
+							}
+						}
+					})
+					break
+				}
+				case 'Declaration': {
+					// Do not process Declarations in atRule preludes
+					// because we will handle them manually
+					if (this.atrulePrelude !== null) {
+						return this.skip
+					}
+
+					totalDeclarations++
+					let complexity = 1
+
+					uniqueDeclarations.add(stringifyNode(node))
+					declarationNesting.push(nestingDepth - 1)
+					uniqueDeclarationNesting.p(nestingDepth - 1, node.loc!)
+
+					if (node.important === true) {
+						importantDeclarations++
+						complexity++
+
+						if (this.atrule && endsWith('keyframes', this.atrule.name)) {
+							importantsInKeyframes++
+							complexity++
+						}
+					}
+
+					declarationComplexities.push(complexity)
+
+					let {
+						property,
+						// @ts-expect-error TODO: fix this
+						loc: { start },
+					} = node
+					let propertyLoc = {
+						start: {
+							line: start.line,
+							column: start.column,
+							offset: start.offset,
+						},
+						end: {
+							offset: start.offset + property.length,
+						},
+					}
+
+					properties.p(property, propertyLoc)
+
+					if (hasVendorPrefix(property)) {
+						propertyVendorPrefixes.p(property, propertyLoc)
+						propertyComplexities.push(2)
+					} else if (isHack(property)) {
+						propertyHacks.p(property, propertyLoc)
+						propertyComplexities.push(2)
+					} else if (isCustom(property)) {
+						customProperties.p(property, propertyLoc)
+						propertyComplexities.push(node.important ? 3 : 2)
+
+						if (node.important === true) {
+							importantCustomProperties.p(property, propertyLoc)
+						}
+					} else {
+						propertyComplexities.push(1)
+					}
+
+					break
+				}
+			}
+
+			if (node.type === Rule || node.type === Atrule) {
+				nestingDepth++
+			}
+		},
+		leave(node: CssNode) {
+			if (node.type === Rule || node.type === Atrule) {
+				nestingDepth--
+			}
+		},
+	})
+
+	let totalUniqueDeclarations = uniqueDeclarations.size
+
+	let totalSelectors = selectorComplexities.size()
+	let specificitiesA = specificityA.aggregate()
+	let specificitiesB = specificityB.aggregate()
+	let specificitiesC = specificityC.aggregate()
+	let totalUniqueSelectors = uniqueSelectors.size
+	let assign = Object.assign
+	let cssLen = css.length
+	let fontFacesCount = fontfaces.length
+	let atRuleComplexity = atRuleComplexities.aggregate()
+	let selectorComplexity = selectorComplexities.aggregate()
+	let declarationComplexity = declarationComplexities.aggregate()
+	let propertyComplexity = propertyComplexities.aggregate()
+	let valueComplexity = valueComplexities.aggregate()
+	let atruleCount = atrules.c()
+
+	return {
+		stylesheet: {
+			sourceLinesOfCode: atruleCount.total + totalSelectors + totalDeclarations + keyframeSelectors.size(),
+			linesOfCode,
+			size: cssLen,
+			complexity: atRuleComplexity.sum + selectorComplexity.sum + declarationComplexity.sum + propertyComplexity.sum + valueComplexity.sum,
+			comments: {
+				total: totalComments,
+				size: commentsSize,
+			},
+			embeddedContent: {
+				size: {
+					total: embedSize,
+					ratio: ratio(embedSize, cssLen),
+				},
+				types: {
+					total: embedTypes.total,
+					totalUnique: embedTypes.unique.size,
+					uniquenessRatio: ratio(embedTypes.unique.size, embedTypes.total),
+					unique: Object.fromEntries(embedTypes.unique),
+				},
+			},
+		},
+		atrules: assign(atruleCount, {
+			fontface: assign(
+				{
+					total: fontFacesCount,
+					totalUnique: fontFacesCount,
+					unique: fontfaces,
+					uniquenessRatio: fontFacesCount === 0 ? 0 : 1,
+				},
+				useLocations
+					? {
+							uniqueWithLocations: fontfaces_with_loc.c().uniqueWithLocations,
+						}
+					: {},
+			),
+			import: imports.c(),
+			media: assign(medias.c(), {
+				browserhacks: mediaBrowserhacks.c(),
+				features: mediaFeatures.c(),
+			}),
+			charset: charsets.c(),
+			supports: assign(supports.c(), {
+				browserhacks: supportsBrowserhacks.c(),
+			}),
+			keyframes: assign(keyframes.c(), {
+				prefixed: assign(prefixedKeyframes.c(), {
+					ratio: ratio(prefixedKeyframes.size(), keyframes.size()),
+				}),
+			}),
+			container: assign(containers.c(), {
+				names: containerNames.c(),
+			}),
+			layer: layers.c(),
+			property: registeredProperties.c(),
+			complexity: atRuleComplexity,
+			nesting: assign(
+				atruleNesting.aggregate(),
+				{
+					items: atruleNesting.toArray(),
+				},
+				uniqueAtruleNesting.c(),
+			),
+		}),
+		rules: {
+			total: totalRules,
+			empty: {
+				total: emptyRules,
+				ratio: ratio(emptyRules, totalRules),
+			},
+			sizes: assign(
+				ruleSizes.aggregate(),
+				{
+					items: ruleSizes.toArray(),
+				},
+				uniqueRuleSize.c(),
+			),
+			nesting: assign(
+				ruleNesting.aggregate(),
+				{
+					items: ruleNesting.toArray(),
+				},
+				uniqueRuleNesting.c(),
+			),
+			selectors: assign(
+				selectorsPerRule.aggregate(),
+				{
+					items: selectorsPerRule.toArray(),
+				},
+				uniqueSelectorsPerRule.c(),
+			),
+			declarations: assign(
+				declarationsPerRule.aggregate(),
+				{
+					items: declarationsPerRule.toArray(),
+				},
+				uniqueDeclarationsPerRule.c(),
+			),
+		},
+		selectors: {
+			total: totalSelectors,
+			totalUnique: totalUniqueSelectors,
+			uniquenessRatio: ratio(totalUniqueSelectors, totalSelectors),
+			specificity: assign(
+				{
+					/** @type Specificity */
+					min: minSpecificity === undefined ? [0, 0, 0] : minSpecificity,
+					/** @type Specificity */
+					max: maxSpecificity === undefined ? [0, 0, 0] : maxSpecificity,
+					/** @type Specificity */
+					sum: [specificitiesA.sum, specificitiesB.sum, specificitiesC.sum],
+					/** @type Specificity */
+					mean: [specificitiesA.mean, specificitiesB.mean, specificitiesC.mean],
+					/** @type Specificity */
+					mode: [specificitiesA.mode, specificitiesB.mode, specificitiesC.mode],
+					/** @type Specificity */
+					items: specificities,
+				},
+				uniqueSpecificities.c(),
+			),
+			complexity: assign(selectorComplexity, uniqueSelectorComplexities.c(), {
+				items: selectorComplexities.toArray(),
+			}),
+			nesting: assign(
+				selectorNesting.aggregate(),
+				{
+					items: selectorNesting.toArray(),
+				},
+				uniqueSelectorNesting.c(),
+			),
+			id: assign(ids.c(), {
+				ratio: ratio(ids.size(), totalSelectors),
+			}),
+			pseudoClasses: pseudoClasses.c(),
+			accessibility: assign(a11y.c(), {
+				ratio: ratio(a11y.size(), totalSelectors),
+			}),
+			keyframes: keyframeSelectors.c(),
+			prefixed: assign(prefixedSelectors.c(), {
+				ratio: ratio(prefixedSelectors.size(), totalSelectors),
+			}),
+			combinators: combinators.c(),
+		},
+		declarations: {
+			total: totalDeclarations,
+			totalUnique: totalUniqueDeclarations,
+			uniquenessRatio: ratio(totalUniqueDeclarations, totalDeclarations),
+			importants: {
+				total: importantDeclarations,
+				ratio: ratio(importantDeclarations, totalDeclarations),
+				inKeyframes: {
+					total: importantsInKeyframes,
+					ratio: ratio(importantsInKeyframes, importantDeclarations),
+				},
+			},
+			complexity: declarationComplexity,
+			nesting: assign(
+				declarationNesting.aggregate(),
+				{
+					items: declarationNesting.toArray(),
+				},
+				uniqueDeclarationNesting.c(),
+			),
+		},
+		properties: assign(properties.c(), {
+			prefixed: assign(propertyVendorPrefixes.c(), {
+				ratio: ratio(propertyVendorPrefixes.size(), properties.size()),
+			}),
+			custom: assign(customProperties.c(), {
+				ratio: ratio(customProperties.size(), properties.size()),
+				importants: assign(importantCustomProperties.c(), {
+					ratio: ratio(importantCustomProperties.size(), customProperties.size()),
+				}),
+			}),
+			browserhacks: assign(propertyHacks.c(), {
+				ratio: ratio(propertyHacks.size(), properties.size()),
+			}),
+			complexity: propertyComplexity,
+		}),
+		values: {
+			colors: assign(colors.count(), {
+				formats: colorFormats.c(),
+			}),
+			gradients: gradients.c(),
+			fontFamilies: fontFamilies.c(),
+			fontSizes: fontSizes.c(),
+			lineHeights: lineHeights.c(),
+			zindexes: zindex.c(),
+			textShadows: textShadows.c(),
+			boxShadows: boxShadows.c(),
+			borderRadiuses: borderRadiuses.count(),
+			animations: {
+				durations: durations.c(),
+				timingFunctions: timingFunctions.c(),
+			},
+			prefixes: vendorPrefixedValues.c(),
+			browserhacks: valueBrowserhacks.c(),
+			units: units.count(),
+			complexity: valueComplexity,
+			keywords: valueKeywords.c(),
+			resets: resets.c(),
+		},
+		__meta__: {
+			parseTime: startAnalysis - startParse,
+			analyzeTime: Date.now() - startAnalysis,
+			total: Date.now() - start,
+		},
+	}
+}
+
+/**
+ * Compare specificity A to Specificity B
+ * @returns 0 when a==b, 1 when a<b, -1 when a>b
+ */
+export function compareSpecificity(a: Specificity, b: Specificity): number {
+	if (a[0] === b[0]) {
+		if (a[1] === b[1]) {
+			return b[2] - a[2]
+		}
+
+		return b[1] - a[1]
+	}
+
+	return b[0] - a[0]
+}
+
+export {
+	getComplexity as selectorComplexity,
+	isPrefixed as isSelectorPrefixed,
+	isAccessibility as isAccessibilitySelector,
+} from './selectors/utils.js'
+
+export { isSupportsBrowserhack, isMediaBrowserhack } from './atrules/atrules.js'
+
+export { isHack as isPropertyHack } from './properties/property-utils.js'
+
+export { isValuePrefixed } from './values/vendor-prefix.js'
+
+export { colorFunctions, colorKeywords, namedColors, systemColors } from './values/colors.js'
+
+export { keywords as cssKeywords } from './values/values.js'
+
+export { hasVendorPrefix } from './vendor-prefix.js'
+
+export { KeywordSet } from './keyword-set.js'
diff --git a/src/keyword-set.test.js b/src/keyword-set.test.js
deleted file mode 100644
index aee7ab35..00000000
--- a/src/keyword-set.test.js
+++ /dev/null
@@ -1,15 +0,0 @@
-import { KeywordSet } from './keyword-set.js'
-import { test } from 'uvu'
-import * as assert from "uvu/assert"
-
-test('happy path', () => {
-	assert.not.ok(new KeywordSet([]).has('a'))
-	expect.not.ok(new KeywordSet([]).has(''))
-	expect.ok(new KeywordSet(['a', 'b']).has('a'))
-	expect.ok(new KeywordSet(['a', 'b']).has('A'))
-	expect.not.ok(new KeywordSet(['a', 'b']).has('aa'))
-
-	expect.ok(new KeywordSet(['currentcolor']).has('currentColor'))
-	expect.ok(new KeywordSet(['marktext']).has('MarkText'))
-	expect.ok(new KeywordSet(['revert-layer']).has('Revert-Layer'))
-})
diff --git a/src/keyword-set.test.ts b/src/keyword-set.test.ts
new file mode 100644
index 00000000..578d51a4
--- /dev/null
+++ b/src/keyword-set.test.ts
@@ -0,0 +1,14 @@
+import { test, expect } from 'vitest'
+import { KeywordSet } from './keyword-set.js'
+
+test('happy path', () => {
+	expect(new KeywordSet([]).has('a')).toEqual(false)
+	expect(new KeywordSet([]).has('')).toEqual(false)
+	expect(new KeywordSet(['a', 'b']).has('a')).toEqual(true)
+	expect(new KeywordSet(['a', 'b']).has('A')).toEqual(true)
+	expect(new KeywordSet(['a', 'b']).has('aa')).toEqual(false)
+
+	expect(new KeywordSet(['currentcolor']).has('currentColor')).toEqual(true)
+	expect(new KeywordSet(['marktext']).has('MarkText')).toEqual(true)
+	expect(new KeywordSet(['revert-layer']).has('Revert-Layer')).toEqual(true)
+})
diff --git a/src/keyword-set.js b/src/keyword-set.ts
similarity index 67%
rename from src/keyword-set.js
rename to src/keyword-set.ts
index e2e399b3..6fe7074b 100644
--- a/src/keyword-set.js
+++ b/src/keyword-set.ts
@@ -2,15 +2,14 @@
  * @description A Set-like construct to search CSS keywords in a case-insensitive way
  */
 export class KeywordSet {
+	set: Set<string>
 
-	/** @param {Lowercase<string>[]} items */
-	constructor(items) {
+	constructor(items: Lowercase<string>[]) {
 		/** @type {Set<string>} */
 		this.set = new Set(items)
 	}
 
-	/** @param {string} item */
-	has(item) {
+	has(item: string): boolean {
 		return this.set.has(item.toLowerCase())
 	}
-}
\ No newline at end of file
+}
diff --git a/src/properties/properties.test.js b/src/properties/properties.test.js
deleted file mode 100644
index 21968946..00000000
--- a/src/properties/properties.test.js
+++ /dev/null
@@ -1,193 +0,0 @@
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
-import { analyze } from '../index.js'
-
-const Properties = suite('Properties')
-
-Properties('counts totals', () => {
-  const fixture = `
-    properties {
-      margin: 0;
-      --custom: 1;
-    }
-
-    @media print {
-      nested {
-        --custom: 2;
-      }
-    }
-  `
-  const actual = analyze(fixture).properties.total
-
-  assert.is(actual, 3)
-})
-
-Properties('calculates uniqueness', () => {
-  const fixture = `
-    properties {
-      margin: 0;
-      --custom: 1;
-    }
-
-    @media print {
-      nested {
-        --custom: 1;
-      }
-    }
-  `
-  const actual = analyze(fixture).properties
-  const expected = {
-    'margin': 1,
-    '--custom': 2,
-  }
-
-  assert.is(actual.totalUnique, 2)
-  assert.equal(actual.unique, expected)
-  assert.is(actual.uniquenessRatio, 2 / 3)
-})
-
-Properties('counts vendor prefixes', () => {
-  const fixture = `
-    prefixed {
-      border-radius: 2px;
-      -webkit-border-radius: 2px;
-      -khtml-border-radius: 2px;
-      -o-border-radius: 2px;
-    }
-
-    @media (min-width: 0) {
-      @supports (-o-border-radius: 2px) {
-        prefixed2 {
-          -o-border-radius: 4px;
-        }
-      }
-    }
-  `
-  const actual = analyze(fixture).properties.prefixed
-  const expected = {
-    '-webkit-border-radius': 1,
-    '-khtml-border-radius': 1,
-    '-o-border-radius': 2,
-  }
-
-  assert.is(actual.total, 4)
-  assert.is(actual.totalUnique, 3)
-  assert.equal(actual.unique, expected)
-  assert.is(actual.ratio, 4 / 5)
-})
-
-Properties('counts browser hacks', () => {
-  const fixture = `
-    hacks {
-      margin: 0;
-      *zoom: 1;
-    }
-
-    @media (min-width: 0) {
-      @supports (-o-border-radius: 2px) {
-        hacks2 {
-          *zoom: 1;
-        }
-      }
-    }
-  `
-  const actual = analyze(fixture).properties.browserhacks
-  const expected = {
-    '*zoom': 2
-  }
-
-  assert.is(actual.total, 2)
-  assert.is(actual.totalUnique, 1)
-  assert.equal(actual.unique, expected)
-  assert.is(actual.ratio, 2 / 3)
-})
-
-Properties('counts custom properties', () => {
-  const fixture = `
-    :root {
-      --yellow-400: yellow;
-    }
-
-    custom {
-      margin: 0;
-      --yellow-400: yellow;
-      color: var(--yellow-400);
-    }
-
-    @media (min-width: 0) {
-      @supports (-o-border-radius: 2px) {
-        custom2 {
-          --green-400: green;
-          color: var(--green-400);
-        }
-      }
-    }
-  `
-  const actual = analyze(fixture).properties.custom
-  const expected = {
-    '--yellow-400': 2,
-    '--green-400': 1,
-  }
-
-  assert.is(actual.total, 3)
-  assert.is(actual.totalUnique, 2)
-  assert.equal(actual.unique, expected)
-  assert.is(actual.ratio, 3 / 6)
-})
-
-Properties('calculates property complexity', () => {
-  const fixture = `
-    .property-complexity-fixture {
-      regular-property: 1;
-      --my-custom-property: 2;
-      *browserhack-property: 2;
-      -webkit-property: 2;
-    }
-  `
-  const actual = analyze(fixture).properties.complexity
-
-  assert.is(actual.max, 2)
-  assert.is(actual.mean, 1.75)
-  assert.is(actual.min, 1)
-  assert.is(actual.mode, 2)
-  assert.is(actual.range, 1)
-  assert.is(actual.sum, 7)
-})
-
-Properties('counts the amount of !important used on custom properties', () => {
-  const fixture = `
-    .property {
-      color: blue;
-      --color1: red;
-      --color2: yellow !important;
-    }
-
-    @media screen {
-      .property {
-        color: blue;
-        --color1: red;
-        --color2: yellow !important;
-      }
-    }
-
-    @layer test {
-      .property {
-        color: blue;
-        --color1: red;
-        --color3: green !important;
-      }
-    }
-  `
-  const actual = analyze(fixture).properties.custom.importants
-
-  assert.is(actual.total, 3)
-  assert.is(actual.totalUnique, 2)
-  assert.is(actual.uniquenessRatio, 2 / 3)
-  assert.is(actual.ratio, 3 / 6)
-  assert.equal(actual.unique, {
-    '--color2': 2,
-    '--color3': 1,
-  })
-})
-
-Properties.run()
\ No newline at end of file
diff --git a/src/properties/properties.test.ts b/src/properties/properties.test.ts
new file mode 100644
index 00000000..dec30b34
--- /dev/null
+++ b/src/properties/properties.test.ts
@@ -0,0 +1,188 @@
+import { test, expect } from 'vitest'
+import { analyze } from '../index.js'
+
+test('counts totals', () => {
+	const fixture = `
+    properties {
+      margin: 0;
+      --custom: 1;
+    }
+
+    @media print {
+      nested {
+        --custom: 2;
+      }
+    }
+  `
+	const actual = analyze(fixture).properties.total
+
+	expect(actual).toEqual(3)
+})
+
+test('calculates uniqueness', () => {
+	const fixture = `
+    properties {
+      margin: 0;
+      --custom: 1;
+    }
+
+    @media print {
+      nested {
+        --custom: 1;
+      }
+    }
+  `
+	const actual = analyze(fixture).properties
+	const expected = {
+		margin: 1,
+		'--custom': 2,
+	}
+
+	expect(actual.totalUnique).toEqual(2)
+	expect(actual.unique).toEqual(expected)
+	expect(actual.uniquenessRatio).toEqual(2 / 3)
+})
+
+test('counts vendor prefixes', () => {
+	const fixture = `
+    prefixed {
+      border-radius: 2px;
+      -webkit-border-radius: 2px;
+      -khtml-border-radius: 2px;
+      -o-border-radius: 2px;
+    }
+
+    @media (min-width: 0) {
+      @supports (-o-border-radius: 2px) {
+        prefixed2 {
+          -o-border-radius: 4px;
+        }
+      }
+    }
+  `
+	const actual = analyze(fixture).properties.prefixed
+	const expected = {
+		'-webkit-border-radius': 1,
+		'-khtml-border-radius': 1,
+		'-o-border-radius': 2,
+	}
+
+	expect(actual.total).toEqual(4)
+	expect(actual.totalUnique).toEqual(3)
+	expect(actual.unique).toEqual(expected)
+	expect(actual.ratio).toEqual(4 / 5)
+})
+
+test('counts browser hacks', () => {
+	const fixture = `
+    hacks {
+      margin: 0;
+      *zoom: 1;
+    }
+
+    @media (min-width: 0) {
+      @supports (-o-border-radius: 2px) {
+        hacks2 {
+          *zoom: 1;
+        }
+      }
+    }
+  `
+	const actual = analyze(fixture).properties.browserhacks
+	const expected = {
+		'*zoom': 2,
+	}
+
+	expect(actual.total).toEqual(2)
+	expect(actual.totalUnique).toEqual(1)
+	expect(actual.unique).toEqual(expected)
+	expect(actual.ratio).toEqual(2 / 3)
+})
+
+test('counts custom properties', () => {
+	const fixture = `
+    :root {
+      --yellow-400: yellow;
+    }
+
+    custom {
+      margin: 0;
+      --yellow-400: yellow;
+      color: var(--yellow-400);
+    }
+
+    @media (min-width: 0) {
+      @supports (-o-border-radius: 2px) {
+        custom2 {
+          --green-400: green;
+          color: var(--green-400);
+        }
+      }
+    }
+  `
+	const actual = analyze(fixture).properties.custom
+	const expected = {
+		'--yellow-400': 2,
+		'--green-400': 1,
+	}
+
+	expect(actual.total).toEqual(3)
+	expect(actual.totalUnique).toEqual(2)
+	expect(actual.unique).toEqual(expected)
+	expect(actual.ratio).toEqual(3 / 6)
+})
+
+test('calculates property complexity', () => {
+	const fixture = `
+    .property-complexity-fixture {
+      regular-property: 1;
+      --my-custom-property: 2;
+      *browserhack-property: 2;
+      -webkit-property: 2;
+    }
+  `
+	const actual = analyze(fixture).properties.complexity
+
+	expect(actual.max).toEqual(2)
+	expect(actual.mean).toEqual(1.75)
+	expect(actual.min).toEqual(1)
+	expect(actual.mode).toEqual(2)
+	expect(actual.range).toEqual(1)
+	expect(actual.sum).toEqual(7)
+})
+
+test('counts the amount of !important used on custom properties', () => {
+	const fixture = `
+    .property {
+      color: blue;
+      --color1: red;
+      --color2: yellow !important;
+    }
+
+    @media screen {
+      .property {
+        color: blue;
+        --color1: red;
+        --color2: yellow !important;
+      }
+    }
+
+    @layer test {
+      .property {
+        color: blue;
+        --color1: red;
+        --color3: green !important;
+      }
+    }
+  `
+	const actual = analyze(fixture).properties.custom.importants
+
+	expect(actual.total).toEqual(3)
+	expect(actual.totalUnique).toEqual(2)
+	expect(actual.uniquenessRatio).toEqual(2 / 3)
+	expect(actual.ratio).toEqual(3 / 6)
+	expect(actual.unique).toEqual({
+		'--color2': 2,
+		'--color3': 1,
+	})
+})
diff --git a/src/properties/property-utils.js b/src/properties/property-utils.js
deleted file mode 100644
index 66030151..00000000
--- a/src/properties/property-utils.js
+++ /dev/null
@@ -1,57 +0,0 @@
-import { hasVendorPrefix } from '../vendor-prefix.js'
-import { endsWith } from '../string-utils.js'
-
-/**
- * @param {string} property
- * @see https://github.com/csstree/csstree/blob/master/lib/utils/names.js#L69
- */
-export function isHack(property) {
-  if (isCustom(property) || hasVendorPrefix(property)) return false
-
-  let code = property.charCodeAt(0)
-
-  return code === 47 // /
-    || code === 42 // *
-    || code === 95 // _
-    || code === 43 // +
-    || code === 38 // &
-    || code === 36 // $
-    || code === 35 // #
-}
-
-export function isCustom(property) {
-  if (property.length < 3) return false
-  // 45 === '-'.charCodeAt(0)
-  return property.charCodeAt(0) === 45 && property.charCodeAt(1) === 45
-}
-
-/**
- * A check to verify that a propery is `basename` or a prefixed
- * version of that, but never a custom property that accidentally
- * ends with the same substring.
- *
- * @example
- * isProperty('animation', 'animation') // true
- * isProperty('animation', '-webkit-animation') // true
- * isProperty('animation', '--my-animation') // false
- *
- * @param {string} basename
- * @param {string} property
- * @returns {boolean} True if `property` equals `basename` without prefix
- */
-export function isProperty(basename, property) {
-  if (isCustom(property)) return false
-  return endsWith(basename, property)
-}
-
-/**
- * Get the basename for a property with a vendor prefix
- * @param {string} property
- * @returns {string} The property name without vendor prefix
- */
-export function basename(property) {
-  if (hasVendorPrefix(property)) {
-    return property.slice(property.indexOf('-', 2) + 1)
-  }
-  return property
-}
diff --git a/src/properties/property-utils.test.js b/src/properties/property-utils.test.js
deleted file mode 100644
index eb42976c..00000000
--- a/src/properties/property-utils.test.js
+++ /dev/null
@@ -1,44 +0,0 @@
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
-import { isHack, isCustom, isProperty } from './property-utils.js'
-
-const PropertyUtils = suite('Property Utils')
-
-PropertyUtils('isHack', () => {
-  assert.ok(isHack('/property'))
-  assert.ok(isHack('//property'))
-  assert.ok(isHack('_property'))
-  assert.ok(isHack('+property'))
-  assert.ok(isHack('*property'))
-  assert.ok(isHack('&property'))
-  assert.ok(isHack('#property'))
-  assert.ok(isHack('$property'))
-
-  assert.not.ok(isHack('property'))
-  assert.not.ok(isHack('-property'))
-  assert.not.ok(isHack('--property'))
-})
-
-PropertyUtils('isCustom', () => {
-  assert.ok(isCustom('--property'))
-  assert.ok(isCustom('--MY-PROPERTY'))
-  assert.ok(isCustom('--x'))
-
-  assert.not.ok(isCustom('property'))
-  assert.not.ok(isCustom('-property'))
-  assert.not.ok(isCustom('-webkit-property'))
-  assert.not.ok(isCustom('-moz-property'))
-})
-
-PropertyUtils('isProperty', () => {
-  assert.ok(isProperty('animation', 'animation'))
-  assert.ok(isProperty('animation', 'ANIMATION'))
-  assert.ok(isProperty('animation', '-webkit-animation'))
-  assert.ok(isProperty('font', '_font'))
-  assert.ok(isProperty('width', '*width'))
-
-  assert.not.ok(isProperty('animation', '--animation'))
-  assert.not.ok(isProperty('property', '--Property'))
-})
-
-PropertyUtils.run()
\ No newline at end of file
diff --git a/src/properties/property-utils.test.ts b/src/properties/property-utils.test.ts
new file mode 100644
index 00000000..1f30a8b3
--- /dev/null
+++ b/src/properties/property-utils.test.ts
@@ -0,0 +1,39 @@
+import { test, expect } from 'vitest'
+import { isHack, isCustom, isProperty } from './property-utils.js'
+
+test('isHack', () => {
+	expect(isHack('/property')).toEqual(true)
+	expect(isHack('//property')).toEqual(true)
+	expect(isHack('_property')).toEqual(true)
+	expect(isHack('+property')).toEqual(true)
+	expect(isHack('*property')).toEqual(true)
+	expect(isHack('&property')).toEqual(true)
+	expect(isHack('#property')).toEqual(true)
+	expect(isHack('$property')).toEqual(true)
+
+	expect(isHack('property')).toEqual(false)
+	expect(isHack('-property')).toEqual(false)
+	expect(isHack('--property')).toEqual(false)
+})
+
+test('isCustom', () => {
+	expect(isCustom('--property')).toEqual(true)
+	expect(isCustom('--MY-PROPERTY')).toEqual(true)
+	expect(isCustom('--x')).toEqual(true)
+
+	expect(isCustom('property')).toEqual(false)
+	expect(isCustom('-property')).toEqual(false)
+	expect(isCustom('-webkit-property')).toEqual(false)
+	expect(isCustom('-moz-property')).toEqual(false)
+})
+
+test('isProperty', () => {
+	expect(isProperty('animation', 'animation')).toEqual(true)
+	expect(isProperty('animation', 'ANIMATION')).toEqual(true)
+	expect(isProperty('animation', '-webkit-animation')).toEqual(true)
+	expect(isProperty('font', '_font')).toEqual(true)
+	expect(isProperty('width', '*width')).toEqual(true)
+
+	expect(isProperty('animation', '--animation')).toEqual(false)
+	expect(isProperty('property', '--Property')).toEqual(false)
+})
diff --git a/src/properties/property-utils.ts b/src/properties/property-utils.ts
new file mode 100644
index 00000000..d09a5afd
--- /dev/null
+++ b/src/properties/property-utils.ts
@@ -0,0 +1,55 @@
+import { hasVendorPrefix } from '../vendor-prefix.js'
+import { endsWith } from '../string-utils.js'
+
+/**
+ * @see https://github.com/csstree/csstree/blob/master/lib/utils/names.js#L69
+ */
+export function isHack(property: string): boolean {
+	if (isCustom(property) || hasVendorPrefix(property)) return false
+
+	let code = property.charCodeAt(0)
+
+	return (
+		code === 47 || // /
+		code === 42 || // *
+		code === 95 || // _
+		code === 43 || // +
+		code === 38 || // &
+		code === 36 || // $
+		code === 35
+	) // #
+}
+
+export function isCustom(property: string): boolean {
+	if (property.length < 3) return false
+	// 45 === '-'.charCodeAt(0)
+	return property.charCodeAt(0) === 45 && property.charCodeAt(1) === 45
+}
+
+/**
+ * A check to verify that a propery is `basename` or a prefixed
+ * version of that, but never a custom property that accidentally
+ * ends with the same substring.
+ *
+ * @example
+ * isProperty('animation', 'animation') // true
+ * isProperty('animation', '-webkit-animation') // true
+ * isProperty('animation', '--my-animation') // false
+ *
+ * @returns True if `property` equals `basename` without prefix
+ */
+export function isProperty(basename: string, property: string): boolean {
+	if (isCustom(property)) return false
+	return endsWith(basename, property)
+}
+
+/**
+ * Get the basename for a property with a vendor prefix
+ * @returns The property name without vendor prefix
+ */
+export function basename(property: string): string {
+	if (hasVendorPrefix(property)) {
+		return property.slice(property.indexOf('-', 2) + 1)
+	}
+	return property
+}
diff --git a/src/rules/rules.test.js b/src/rules/rules.test.js
deleted file mode 100644
index 4b3de030..00000000
--- a/src/rules/rules.test.js
+++ /dev/null
@@ -1,461 +0,0 @@
-import { suite } from 'uvu';
-import * as assert from 'uvu/assert';
-import { analyze } from '../index.js'
-
-const Rules = suite('Rules')
-
-Rules('should count rules', () => {
-  assert.is(analyze(`
-    html {
-      color: black;
-    }
-    test {}
-  `).rules.total, 2)
-})
-
-Rules('should handle CSS without rules', () => {
-  const fixture = `@media (min-width: 0px) {}`
-  const actual = analyze(fixture)
-  const expected = {
-    total: 0,
-    empty: {
-      total: 0,
-      ratio: 0
-    },
-    sizes: {
-      min: 0,
-      max: 0,
-      mean: 0,
-      mode: 0,
-      range: 0,
-      sum: 0,
-      items: [],
-      unique: {},
-      total: 0,
-      totalUnique: 0,
-      uniquenessRatio: 0,
-    },
-    selectors: {
-      min: 0,
-      max: 0,
-      mean: 0,
-      mode: 0,
-      range: 0,
-      sum: 0,
-      items: [],
-      unique: {},
-      total: 0,
-      totalUnique: 0,
-      uniquenessRatio: 0,
-    },
-    declarations: {
-      min: 0,
-      max: 0,
-      mean: 0,
-      mode: 0,
-      range: 0,
-      sum: 0,
-      items: [],
-      unique: {},
-      total: 0,
-      totalUnique: 0,
-      uniquenessRatio: 0,
-    },
-    nesting: {
-      min: 0,
-      max: 0,
-      mean: 0,
-      mode: 0,
-      range: 0,
-      sum: 0,
-      items: [],
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-    }
-  }
-  assert.equal(actual.rules, expected)
-})
-
-Rules('counts sizes of rules', () => {
-  const result = analyze(`
-    x {
-      a: 1;
-    }
-    a,
-    b {
-      a: 1;
-      b: 2;
-    }
-    c,
-    d,
-    e {
-      a: 1;
-      b: 2;
-      c: 3;
-    }
-
-    @media print {
-      @supports (display: grid) {
-        f {
-          a: 1;
-          b: 2;
-        }
-      }
-    }
-  `)
-  const actual = result.rules.sizes
-
-  assert.equal(actual, {
-    min: 2,
-    max: 6,
-    mean: 3.75,
-    mode: 3.75,
-    range: 4,
-    sum: 15,
-    items: [2, 4, 6, 3],
-    unique: {
-      2: 1,
-      4: 1,
-      6: 1,
-      3: 1,
-    },
-    total: 4,
-    totalUnique: 4,
-    uniquenessRatio: 4 / 4,
-  })
-})
-
-Rules('should count empty rules', () => {
-  assert.is(1, analyze(`test{}`).rules.empty.total)
-  assert.is(analyze('@media print {}').rules.empty.total, 0)
-  assert.is(analyze(`
-    @media print {
-      empty {}
-    }
-  `).rules.empty.total, 1)
-  assert.is(analyze('test { color: red; }').rules.empty.total, 0)
-})
-
-Rules('calculate the minimum selectors', () => {
-  assert.is(analyze(`
-    html {}
-    a,
-    b {}
-  `).rules.selectors.min, 1)
-})
-
-Rules('calculate the maximum selectors', () => {
-  assert.is(analyze(`
-    html {}
-    a,
-    b {}
-  `).rules.selectors.max, 2)
-})
-
-Rules('calculate the mode of selectors', () => {
-  assert.is(analyze(`
-    html {}
-    a,
-    b {}
-    x {}
-  `).rules.selectors.mode, 1)
-})
-
-Rules('calculate the mean of selectors', () => {
-  assert.is(analyze(`
-    html {}
-    a,
-    b {}
-  `).rules.selectors.mean, 1.5)
-})
-
-Rules('calculate the range of selectors', () => {
-  assert.is(analyze(`
-    html {}
-
-    a,
-    b {}
-
-    a,
-    b,
-    c {}
-  `).rules.selectors.range, 2)
-})
-
-
-Rules('calculate the minimum declarations', () => {
-  assert.is(analyze(`
-    html {}
-    test {
-      color: red;
-    }
-  `).rules.declarations.min, 0)
-  assert.is(analyze('@media print {}').rules.declarations.min, 0)
-})
-
-Rules('calculate the maximum declarations', () => {
-  assert.is(analyze(`
-    html {}
-    test {
-      a: 1;
-      b: 2;
-      c: 3;
-    }
-  `).rules.declarations.max, 3)
-
-  assert.is(analyze(`
-    html {}
-    test {
-      a: 1;
-      b: 2;
-      c: 3;
-    }
-
-    @media print {
-      test {
-        a: 1;
-        b: 2;
-        c: 3;
-        d: 4;
-      }
-    }
-  `).rules.declarations.max, 4)
-})
-
-Rules('calculate the mode of declarations', () => {
-  assert.is(analyze(`
-    html {
-      a: 1;
-    }
-    test {
-      a: 1;
-    }
-    test {
-      a: 1;
-      b: 2;
-    }
-  `).rules.declarations.mode, 1)
-})
-
-Rules('calculate the mean of declarations', () => {
-  assert.is(analyze(`
-    html {
-      a: 1;
-    }
-    a {
-      a: 1;
-      b: 2;
-    }
-    b {
-      a: 1;
-      b: 2;
-      c: 3;
-    }
-  `).rules.declarations.mean, 2)
-})
-
-Rules('calculate the range of declarations', () => {
-  assert.is(analyze(`
-    html {
-      a: 1;
-    }
-    a {
-      a: 1;
-      b: 2;
-    }
-    b {
-      a: 1;
-      b: 2;
-      c: 3;
-    }
-  `).rules.declarations.range, 2)
-})
-
-Rules('return a list of declaration counts per rule', () => {
-  const actual = analyze(`
-    html {
-      a: 1;
-    }
-    a {
-      a: 1;
-      b: 2;
-    }
-    b {
-      a: 1;
-      b: 2;
-      c: 3;
-    }
-
-    @media print {
-      @supports (display: grid) {
-        c {
-          a: 1;
-          b: 2;
-        }
-        d {}
-      }
-    }
-  `).rules.declarations.items
-  const expected = [1, 2, 3, 2, 0]
-  assert.equal(actual, expected)
-})
-
-Rules('return a list of selectors counts per rule', () => {
-  const actual = analyze(`
-    x {
-      a: 1;
-    }
-    a,
-    b {
-      a: 1;
-      b: 2;
-    }
-    c,
-    d,
-    e {
-      a: 1;
-      b: 2;
-      c: 3;
-    }
-
-    @media print {
-      @supports (display: grid) {
-        f {
-          a: 1;
-          b: 2;
-        }
-      }
-    }
-  `).rules.declarations.items
-  const expected = [1, 2, 3, 2]
-  assert.equal(actual, expected)
-})
-
-Rules('counts unique numbers of selectors per rule', () => {
-  const result = analyze(`
-    x {
-      a: 1;
-    }
-    a,
-    b {
-      a: 1;
-      b: 2;
-    }
-    c,
-    d,
-    e {
-      a: 1;
-      b: 2;
-      c: 3;
-    }
-
-    @media print {
-      @supports (display: grid) {
-        f {
-          a: 1;
-          b: 2;
-        }
-      }
-    }
-  `).rules.selectors
-
-  assert.equal(result.unique, {
-    1: 2,
-    2: 1,
-    3: 1,
-  })
-  assert.is(result.totalUnique, 3)
-  assert.is(result.uniquenessRatio, 3 / 4)
-})
-
-Rules('counts unique numbers of declarations per rule', () => {
-  const result = analyze(`
-    x {
-      a: 1;
-    }
-    a,
-    b {
-      a: 1;
-      b: 2;
-    }
-    c,
-    d,
-    e {
-      a: 1;
-      b: 2;
-      c: 3;
-    }
-
-    @media print {
-      @supports (display: grid) {
-        f {
-          a: 1;
-          b: 2;
-        }
-      }
-    }
-  `).rules.declarations
-
-  assert.equal(result.unique, {
-    1: 1,
-    2: 2,
-    3: 1,
-  })
-  assert.is(result.totalUnique, 3)
-  assert.is(result.uniquenessRatio, 3 / 4)
-})
-
-
-
-Rules('tracks nesting depth', () => {
-  const fixture = `
-    a {
-      color: red;
-    }
-
-    b {
-      color: green;
-
-      &:hover {
-        color: blue;
-      }
-
-      color: deepskyblue;
-
-      @container (width > 400px) {
-        color: rebeccapurple;
-      }
-    }
-
-    @media print {
-      @supports (display: grid) {
-        c {
-          color: orange;
-        }
-      }
-    }
-  `
-  const actual = analyze(fixture).rules.nesting
-  const expected = {
-    min: 0,
-    max: 2,
-    mean: 0.75,
-    mode: 0,
-    range: 2,
-    sum: 3,
-    items: [0, 0, 1, 2],
-    total: 4,
-    totalUnique: 3,
-    unique: {
-      0: 2,
-      1: 1,
-      2: 1,
-    },
-    uniquenessRatio: 3 / 4,
-  }
-  assert.equal(actual, expected)
-})
-
-Rules.run()
\ No newline at end of file
diff --git a/src/rules/rules.test.ts b/src/rules/rules.test.ts
new file mode 100644
index 00000000..6d62ba8e
--- /dev/null
+++ b/src/rules/rules.test.ts
@@ -0,0 +1,478 @@
+import { test, expect } from 'vitest'
+import { analyze } from '../index.js'
+
+test('should count rules', () => {
+	let actual = analyze(`
+    html {
+      color: black;
+    }
+    test {}
+  `).rules.total
+	expect(actual).toEqual(2)
+})
+
+test('should handle CSS without rules', () => {
+	const fixture = `@media (min-width: 0px) {}`
+	const actual = analyze(fixture).rules
+	const expected = {
+		total: 0,
+		empty: {
+			total: 0,
+			ratio: 0,
+		},
+		sizes: {
+			min: 0,
+			max: 0,
+			mean: 0,
+			mode: 0,
+			range: 0,
+			sum: 0,
+			items: [],
+			unique: {},
+			total: 0,
+			totalUnique: 0,
+			uniquenessRatio: 0,
+		},
+		selectors: {
+			min: 0,
+			max: 0,
+			mean: 0,
+			mode: 0,
+			range: 0,
+			sum: 0,
+			items: [],
+			unique: {},
+			total: 0,
+			totalUnique: 0,
+			uniquenessRatio: 0,
+		},
+		declarations: {
+			min: 0,
+			max: 0,
+			mean: 0,
+			mode: 0,
+			range: 0,
+			sum: 0,
+			items: [],
+			unique: {},
+			total: 0,
+			totalUnique: 0,
+			uniquenessRatio: 0,
+		},
+		nesting: {
+			min: 0,
+			max: 0,
+			mean: 0,
+			mode: 0,
+			range: 0,
+			sum: 0,
+			items: [],
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+		},
+	}
+	expect(actual).toEqual(expected)
+})
+
+test('counts sizes of rules', () => {
+	const actual = analyze(`
+    x {
+      a: 1;
+    }
+    a,
+    b {
+      a: 1;
+      b: 2;
+    }
+    c,
+    d,
+    e {
+      a: 1;
+      b: 2;
+      c: 3;
+    }
+
+    @media print {
+      @supports (display: grid) {
+        f {
+          a: 1;
+          b: 2;
+        }
+      }
+    }
+  `).rules.sizes
+
+	let expected = {
+		min: 2,
+		max: 6,
+		mean: 3.75,
+		mode: 3.75,
+		range: 4,
+		sum: 15,
+		items: [2, 4, 6, 3],
+		unique: {
+			2: 1,
+			4: 1,
+			6: 1,
+			3: 1,
+		},
+		total: 4,
+		totalUnique: 4,
+		uniquenessRatio: 4 / 4,
+	}
+	expect(actual).toEqual(expected)
+})
+
+test('should count empty rules', () => {
+	expect(analyze(`test{}`).rules.empty.total).toEqual(1)
+	expect(analyze('@media print {}').rules.empty.total).toEqual(0)
+	expect(
+		analyze(`
+    @media print {
+      empty {}
+    }
+  `).rules.empty.total,
+	).toEqual(1)
+	expect(analyze('test { color: red; }').rules.empty.total).toEqual(0)
+})
+
+test('calculate the minimum selectors', () => {
+	expect(
+		analyze(`
+    html {}
+    a,
+    b {}
+  `).rules.selectors.min,
+	).toEqual(1)
+})
+
+test('calculate the maximum selectors', () => {
+	expect(
+		analyze(`
+    html {}
+    a,
+    b {}
+  `).rules.selectors.max,
+	).toEqual(2)
+})
+
+test('calculate the mode of selectors', () => {
+	expect(
+		analyze(`
+    html {}
+    a,
+    b {}
+    x {}
+  `).rules.selectors.mode,
+	).toEqual(1)
+})
+
+test('calculate the mean of selectors', () => {
+	expect(
+		analyze(`
+    html {}
+    a,
+    b {}
+  `).rules.selectors.mean,
+	).toEqual(1.5)
+})
+
+test('calculate the range of selectors', () => {
+	expect(
+		analyze(`
+    html {}
+
+    a,
+    b {}
+
+    a,
+    b,
+    c {}
+  `).rules.selectors.range,
+	).toEqual(2)
+})
+
+test('calculate the minimum declarations', () => {
+	expect(
+		analyze(`
+    html {}
+    test {
+      color: red;
+    }
+  `).rules.declarations.min,
+	).toEqual(0)
+	expect(analyze('@media print {}').rules.declarations.min).toEqual(0)
+})
+
+test('calculate the maximum declarations', () => {
+	expect(
+		analyze(`
+    html {}
+    test {
+      a: 1;
+      b: 2;
+      c: 3;
+    }
+  `).rules.declarations.max,
+	).toEqual(3)
+
+	expect(
+		analyze(`
+    html {}
+    test {
+      a: 1;
+      b: 2;
+      c: 3;
+    }
+
+    @media print {
+      test {
+        a: 1;
+        b: 2;
+        c: 3;
+        d: 4;
+      }
+    }
+  `).rules.declarations.max,
+	).toEqual(4)
+})
+
+test('calculate the mode of declarations', () => {
+	expect(
+		analyze(`
+    html {
+      a: 1;
+    }
+    test {
+      a: 1;
+    }
+    test {
+      a: 1;
+      b: 2;
+    }
+  `).rules.declarations.mode,
+	).toEqual(1)
+})
+
+test('calculate the mean of declarations', () => {
+	expect(
+		analyze(`
+    html {
+      a: 1;
+    }
+    a {
+      a: 1;
+      b: 2;
+    }
+    b {
+      a: 1;
+      b: 2;
+      c: 3;
+    }
+  `).rules.declarations.mean,
+	).toEqual(2)
+})
+
+test('calculate the range of declarations', () => {
+	expect(
+		analyze(`
+    html {
+      a: 1;
+    }
+    a {
+      a: 1;
+      b: 2;
+    }
+    b {
+      a: 1;
+      b: 2;
+      c: 3;
+    }
+  `).rules.declarations.range,
+	).toEqual(2)
+})
+
+test('return a list of declaration counts per rule', () => {
+	const actual = analyze(`
+    html {
+      a: 1;
+    }
+    a {
+      a: 1;
+      b: 2;
+    }
+    b {
+      a: 1;
+      b: 2;
+      c: 3;
+    }
+
+    @media print {
+      @supports (display: grid) {
+        c {
+          a: 1;
+          b: 2;
+        }
+        d {}
+      }
+    }
+  `).rules.declarations.items
+	const expected = [1, 2, 3, 2, 0]
+	expect(actual).toEqual(expected)
+})
+
+test('return a list of selectors counts per rule', () => {
+	const actual = analyze(`
+    x {
+      a: 1;
+    }
+    a,
+    b {
+      a: 1;
+      b: 2;
+    }
+    c,
+    d,
+    e {
+      a: 1;
+      b: 2;
+      c: 3;
+    }
+
+    @media print {
+      @supports (display: grid) {
+        f {
+          a: 1;
+          b: 2;
+        }
+      }
+    }
+  `).rules.declarations.items
+	const expected = [1, 2, 3, 2]
+	expect(actual).toEqual(expected)
+})
+
+test('counts unique numbers of selectors per rule', () => {
+	const result = analyze(`
+    x {
+      a: 1;
+    }
+    a,
+    b {
+      a: 1;
+      b: 2;
+    }
+    c,
+    d,
+    e {
+      a: 1;
+      b: 2;
+      c: 3;
+    }
+
+    @media print {
+      @supports (display: grid) {
+        f {
+          a: 1;
+          b: 2;
+        }
+      }
+    }
+  `).rules.selectors
+
+	expect(result.unique).toEqual({
+		1: 2,
+		2: 1,
+		3: 1,
+	})
+	expect(result.totalUnique).toEqual(3)
+	expect(result.uniquenessRatio).toEqual(3 / 4)
+})
+
+test('counts unique numbers of declarations per rule', () => {
+	const result = analyze(`
+    x {
+      a: 1;
+    }
+    a,
+    b {
+      a: 1;
+      b: 2;
+    }
+    c,
+    d,
+    e {
+      a: 1;
+      b: 2;
+      c: 3;
+    }
+
+    @media print {
+      @supports (display: grid) {
+        f {
+          a: 1;
+          b: 2;
+        }
+      }
+    }
+  `).rules.declarations
+
+	expect(result.unique).toEqual({
+		1: 1,
+		2: 2,
+		3: 1,
+	})
+	expect(result.totalUnique).toEqual(3)
+	expect(result.uniquenessRatio).toEqual(3 / 4)
+})
+
+test('tracks nesting depth', () => {
+	const fixture = `
+    a {
+      color: red;
+    }
+
+    b {
+      color: green;
+
+      &:hover {
+        color: blue;
+      }
+
+      color: deepskyblue;
+
+      @container (width > 400px) {
+        color: rebeccapurple;
+      }
+    }
+
+    @media print {
+      @supports (display: grid) {
+        c {
+          color: orange;
+        }
+      }
+    }
+  `
+	const actual = analyze(fixture).rules.nesting
+	const expected = {
+		min: 0,
+		max: 2,
+		mean: 0.75,
+		mode: 0,
+		range: 2,
+		sum: 3,
+		items: [0, 0, 1, 2],
+		total: 4,
+		totalUnique: 3,
+		unique: {
+			0: 2,
+			1: 1,
+			2: 1,
+		},
+		uniquenessRatio: 3 / 4,
+	}
+	expect(actual).toEqual(expected)
+})
diff --git a/src/selectors/complexity.test.js b/src/selectors/complexity.test.js
deleted file mode 100644
index 29660af7..00000000
--- a/src/selectors/complexity.test.js
+++ /dev/null
@@ -1,147 +0,0 @@
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
-import { analyze } from '../index.js'
-
-const Complexity = suite('Selector Complexity')
-
-const fixture = `
-  *,
-  * + *,
-  a,
-  a b,
-  a + b,
-  a ~ b,
-  #id,
-  .className,
-  [attr],
-  [attr=value],
-  :where(#id, .class),
-  :where(#a #b #c #d #e #f #g #h #i #j #k #l #m #n #o #p #q #r #s #t #u #v #w #x #y #z),
-  main > :is(h1, h2),
-  input[type=text]::-webkit-input-placeholder,
-  ::-webkit-scrollbar,
-  :-moz-any(header, footer) {}
-`
-
-Complexity('calculates complexity', () => {
-  const actual = analyze(fixture).selectors.complexity.items
-  const expected = [
-    1,
-    3,
-    1,
-    3,
-    3,
-    3,
-    1,
-    1,
-    1,
-    2,
-    3,
-    52,
-    5,
-    5,
-    2,
-    4,
-  ]
-
-  assert.equal(actual, expected)
-})
-
-Complexity('calculates complexity with vendor prefixes', () => {
-  const actual = analyze(`
-  input[type=text]::-webkit-input-placeholder,
-  ::-webkit-scrollbar,
-  .site-header .main-nav:hover>ul>li:nth-child(1) svg,
-  :-moz-any(header, footer) {}
-
-  /* not vendor prefixed */
-  no-prefix,
-  fake-webkit,
-  .-mt-px,
-  .-space-x-1,
-  .-pd-translate-y-2,
-  .-pd-translate-x-full {}
-  `).selectors.complexity
-
-  assert.equal(actual.unique, {
-    '1': 6,
-    '5': 1,
-    '2': 1,
-    '12': 1,
-    '4': 1,
-  })
-})
-
-Complexity('calculates complexity uniqueness', () => {
-  const actual = analyze(fixture).selectors.complexity
-  const expected = {
-    '1': 5,
-    '2': 2,
-    '3': 5,
-    '4': 1,
-    '5': 2,
-    '52': 1,
-  }
-
-  assert.is(actual.totalUnique, 6)
-  assert.is(actual.uniquenessRatio, 6 / 16)
-  assert.equal(actual.unique, expected)
-})
-
-Complexity('calculates the lowest complexity', () => {
-  const fixture = `
-    #test,
-    .me,
-    now,
-    [crazy] ~ .selector > for [no|="good"] {}
-  `
-  const actual = analyze(fixture).selectors.complexity.min
-  assert.equal(actual, 1)
-})
-
-Complexity('calculates the highest complexity', () => {
-  const fixture = `
-    #test,
-    .me,
-    now,
-    [crazy] ~ .selector > for [no|="good"] {}
-  `
-  const actual = analyze(fixture).selectors.complexity.max
-  assert.equal(actual, 8)
-})
-
-Complexity('calculates the complexity mean', () => {
-  const fixture = `
-    #test,
-    .me,
-    now,
-    [crazy] ~ .selector > for [no|="good"] {}
-  `
-  const result = analyze(fixture)
-  const actual = result.selectors.complexity.mean
-  assert.equal(actual, (1 + 1 + 1 + 8) / 4)
-})
-
-Complexity('calculates the complexity mode', () => {
-  const fixture = `
-    #test,
-    .me,
-    now,
-    [crazy] ~ .selector > for [no|="good"] {}
-  `
-  const actual = analyze(fixture).selectors.complexity.mode
-  assert.equal(actual, 1)
-})
-
-Complexity('calculates total complexity', () => {
-  const fixture = `
-    #test,
-    .me,
-    now,
-    [crazy] ~ .selector > for [no|="good"] {}
-  `
-  const actual = analyze(fixture).selectors.complexity.sum
-  assert.equal(actual, 11)
-})
-
-Complexity.run()
\ No newline at end of file
diff --git a/src/selectors/complexity.test.ts b/src/selectors/complexity.test.ts
new file mode 100644
index 00000000..aaac5f26
--- /dev/null
+++ b/src/selectors/complexity.test.ts
@@ -0,0 +1,125 @@
+import { test, expect } from 'vitest'
+import { analyze } from '../index.js'
+
+const fixture = `
+  *,
+  * + *,
+  a,
+  a b,
+  a + b,
+  a ~ b,
+  #id,
+  .className,
+  [attr],
+  [attr=value],
+  :where(#id, .class),
+  :where(#a #b #c #d #e #f #g #h #i #j #k #l #m #n #o #p #q #r #s #t #u #v #w #x #y #z),
+  main > :is(h1, h2),
+  input[type=text]::-webkit-input-placeholder,
+  ::-webkit-scrollbar,
+  :-moz-any(header, footer) {}
+`
+
+test('calculates complexity', () => {
+	const actual = analyze(fixture).selectors.complexity.items
+	const expected = [1, 3, 1, 3, 3, 3, 1, 1, 1, 2, 3, 52, 5, 5, 2, 4]
+
+	expect(actual).toEqual(expected)
+})
+
+test('calculates complexity with vendor prefixes', () => {
+	const actual = analyze(`
+  input[type=text]::-webkit-input-placeholder,
+  ::-webkit-scrollbar,
+  .site-header .main-nav:hover>ul>li:nth-child(1) svg,
+  :-moz-any(header, footer) {}
+
+  /* not vendor prefixed */
+  no-prefix,
+  fake-webkit,
+  .-mt-px,
+  .-space-x-1,
+  .-pd-translate-y-2,
+  .-pd-translate-x-full {}
+  `).selectors.complexity
+
+	expect(actual.unique).toEqual({
+		1: 6,
+		5: 1,
+		2: 1,
+		12: 1,
+		4: 1,
+	})
+})
+
+test('calculates complexity uniqueness', () => {
+	const actual = analyze(fixture).selectors.complexity
+	const expected = {
+		1: 5,
+		2: 2,
+		3: 5,
+		4: 1,
+		5: 2,
+		52: 1,
+	}
+
+	expect(actual.totalUnique).toBe(6)
+	expect(actual.uniquenessRatio).toBe(6 / 16)
+	expect(actual.unique).toEqual(expected)
+})
+
+test('calculates the lowest complexity', () => {
+	const fixture = `
+    #test,
+    .me,
+    now,
+    [crazy] ~ .selector > for [no|="good"] {}
+  `
+	const actual = analyze(fixture).selectors.complexity.min
+	expect(actual).toBe(1)
+})
+
+test('calculates the highest complexity', () => {
+	const fixture = `
+    #test,
+    .me,
+    now,
+    [crazy] ~ .selector > for [no|="good"] {}
+  `
+	const actual = analyze(fixture).selectors.complexity.max
+	expect(actual).toBe(8)
+})
+
+test('calculates the complexity mean', () => {
+	const fixture = `
+    #test,
+    .me,
+    now,
+    [crazy] ~ .selector > for [no|="good"] {}
+  `
+	const result = analyze(fixture)
+	const actual = result.selectors.complexity.mean
+	expect(actual).toBe((1 + 1 + 1 + 8) / 4)
+})
+
+test('calculates the complexity mode', () => {
+	const fixture = `
+    #test,
+    .me,
+    now,
+    [crazy] ~ .selector > for [no|="good"] {}
+  `
+	const actual = analyze(fixture).selectors.complexity.mode
+	expect(actual).toBe(1)
+})
+
+test('calculates total complexity', () => {
+	const fixture = `
+    #test,
+    .me,
+    now,
+    [crazy] ~ .selector > for [no|="good"] {}
+  `
+	const actual = analyze(fixture).selectors.complexity.sum
+	expect(actual).toBe(11)
+})
diff --git a/src/selectors/pseudos.test.js b/src/selectors/pseudos.test.ts
similarity index 59%
rename from src/selectors/pseudos.test.js
rename to src/selectors/pseudos.test.ts
index a3024af1..aaf3067d 100644
--- a/src/selectors/pseudos.test.js
+++ b/src/selectors/pseudos.test.ts
@@ -1,9 +1,6 @@
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
+import { test, expect } from 'vitest'
 import { analyze } from '../index.js'
 
-let test = suite('Selector Pseudo Classes')
-
 test('calculates pseudo classes', () => {
 	const actual = analyze(`
 		a,
@@ -12,48 +9,46 @@ test('calculates pseudo classes', () => {
 		a:lang(en),
 		a:dir(ltr),
 		a:dir(ltr),
-		a:has(.thing) {}`
-	).selectors.pseudoClasses
+		a:has(.thing) {}`).selectors.pseudoClasses
 	let expected = {
 		total: 6,
 		totalUnique: 5,
 		uniquenessRatio: 5 / 6,
 		unique: {
-			'hover': 1,
-			'active': 1,
-			'lang': 1,
-			'dir': 2,
-			'has': 1
+			hover: 1,
+			active: 1,
+			lang: 1,
+			dir: 2,
+			has: 1,
 		},
 	}
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
 test('logs the whole parent selector when using locations', () => {
-	let actual = analyze(`
+	let actual = analyze(
+		`
 		a:hover,
 		a:lang(en) {}`,
-		{ useLocations: true }
+		{ useLocations: true },
 	).selectors.pseudoClasses.uniqueWithLocations
 	let expected = {
-		'hover': [
+		hover: [
 			{
 				line: 2,
 				column: 3,
 				offset: 3,
 				length: 7,
-			}
+			},
 		],
-		'lang': [
+		lang: [
 			{
 				line: 3,
 				column: 3,
 				offset: 14,
 				length: 10,
-			}
-		]
+			},
+		],
 	}
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
-
-test.run()
diff --git a/src/selectors/selectors.test.js b/src/selectors/selectors.test.js
deleted file mode 100644
index 813c7c72..00000000
--- a/src/selectors/selectors.test.js
+++ /dev/null
@@ -1,592 +0,0 @@
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
-import { analyze } from '../index.js'
-
-const Selectors = suite('Selectors')
-
-Selectors('are analyzed', () => {
-  const fixture = `
-    rule {
-      color: green;
-    }
-
-    @media print {
-      @media (min-width: 1000px) {
-        @supports (display: grid) {
-          another-rule {
-            color: purple;
-          }
-        }
-      }
-    }
-  `
-  const actual = analyze(fixture).selectors
-
-  assert.equal(actual.total, 2)
-  assert.equal(actual.totalUnique, 2)
-})
-
-Selectors('handles CSS without selectors', () => {
-  const fixture = `
-    @font-face {
-      font-family: url('/test');
-      font-family: test;
-    }
-  `
-  const actual = analyze(fixture).selectors
-  const expected = {
-    total: 0,
-    totalUnique: 0,
-    uniquenessRatio: 0,
-    specificity: {
-      sum: [0, 0, 0],
-      min: [0, 0, 0],
-      max: [0, 0, 0],
-      mean: [0, 0, 0],
-      mode: [0, 0, 0],
-      items: [],
-      unique: {},
-      total: 0,
-      totalUnique: 0,
-      uniquenessRatio: 0,
-    },
-    complexity: {
-      min: 0,
-      max: 0,
-      mean: 0,
-      mode: 0,
-      range: 0,
-      sum: 0,
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-      items: [],
-    },
-    id: {
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-      ratio: 0,
-    },
-    pseudoClasses: {
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-    },
-    accessibility: {
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-      ratio: 0,
-    },
-    keyframes: {
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-    },
-    prefixed: {
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-      ratio: 0,
-    },
-    combinators: {
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-    },
-    nesting: {
-      min: 0,
-      max: 0,
-      mean: 0,
-      mode: 0,
-      range: 0,
-      sum: 0,
-      items: [],
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-    },
-  }
-  assert.equal(actual, expected)
-})
-
-Selectors('have their complexity calculated', () => {
-  const fixture = `
-    rule {
-      color: green;
-    }
-
-    @media print {
-      @media (min-width: 1000px) {
-        @supports (display: grid) {
-          another-rule {
-            color: purple;
-          }
-        }
-      }
-    }
-  `
-  const actual = analyze(fixture).selectors.complexity.items
-  const expected = [1, 1]
-
-  assert.equal(actual, expected)
-})
-
-Selectors('have their specificity calculated', () => {
-  const fixture = `
-    rule {
-      color: green;
-    }
-
-    * {
-      color: brown;
-    }
-
-    @media print {
-      @media (min-width: 1000px) {
-        @supports (display: grid) {
-          another-rule {
-            color: purple;
-          }
-        }
-      }
-    }
-  `
-  const actual = analyze(fixture)
-  const expected = [
-    [0, 0, 1],
-    [0, 0, 0],
-    [0, 0, 1]
-  ]
-
-  assert.equal(actual.selectors.specificity.items, expected)
-  assert.equal(actual.selectors.total, 3)
-})
-
-Selectors('calculates selector uniqueness', () => {
-  const fixture = `
-    a {}
-    b {}
-
-    @media print {
-      b {}
-      c {}
-    }
-  `
-  const actual = analyze(fixture).selectors
-
-  assert.is(actual.total, 4)
-  assert.is(actual.totalUnique, 3)
-  assert.is(actual.uniquenessRatio, 3 / 4)
-})
-
-Selectors('counts <keyframes-selector>s', () => {
-  const fixture = `
-    myElement1 {
-      opacity: 1;
-    }
-
-    @keyframes test1 {
-      from {
-        opacity: 1;
-      }
-      50% {
-        opacity: 0;
-      }
-      to {
-        opacity: 1;
-      }
-    }
-
-    @media only screen {
-      myElement2 {
-        opacity: 1;
-      }
-
-      @keyframes test2 {
-        from {
-          opacity: 0.1;
-        }
-      }
-    }
-  `
-  const actual = analyze(fixture).selectors
-  assert.is(actual.total, 2)
-  assert.equal(actual.keyframes, {
-    total: 4,
-    totalUnique: 3,
-    unique: {
-      from: 2,
-      to: 1,
-      '50%': 1
-    },
-    uniquenessRatio: 3 / 4,
-  })
-})
-
-Selectors('counts ID selectors', () => {
-  const fixture = `
-    #myId,
-    #myId,
-    element#id,
-    #multiple #ids { }
-
-    /* Not an ID */
-    [href="#hash"] { }
-  `
-  const actual = analyze(fixture).selectors.id
-  const expected = {
-    total: 4,
-    totalUnique: 3,
-    unique: {
-      '#myId': 2,
-      'element#id': 1,
-      '#multiple #ids': 1,
-    },
-    uniquenessRatio: 3 / 4,
-    ratio: 4 / 5
-  }
-
-  assert.equal(actual, expected)
-})
-
-Selectors('counts Accessibility selectors', () => {
-  const fixture = `
-    [aria-hidden],
-    img[role="presentation"],
-    .selector:not([role="tablist"]),
-    body.intent-mouse·[role=tabpanel][tabindex="0"]:focus,
-
-    /* false positives */
-    img[loading="lazy"],
-    [hidden] {}
-  `
-  const actual = analyze(fixture).selectors.accessibility
-  const expected = {
-    total: 4,
-    totalUnique: 4,
-    unique: {
-      '[aria-hidden]': 1,
-      'img[role="presentation"]': 1,
-      '.selector:not([role="tablist"])': 1,
-      'body.intent-mouse·[role=tabpanel][tabindex="0"]:focus': 1,
-    },
-    uniquenessRatio: 1 / 1,
-    ratio: 4 / 6,
-  }
-
-  assert.equal(actual, expected)
-})
-
-Selectors('handles emoji selectors', () => {
-  const fixture = `
-    .💩 {}
-  `
-  const result = analyze(fixture)
-  const actual = result.selectors
-
-  const expected = {
-    total: 1,
-    totalUnique: 1,
-    uniquenessRatio: 1,
-    specificity: {
-      sum: [0, 1, 0],
-      min: [0, 1, 0],
-      max: [0, 1, 0],
-      mean: [0, 1, 0],
-      mode: [0, 1, 0],
-      items: [[0, 1, 0]],
-      unique: {
-        '0,1,0': 1,
-      },
-      total: 1,
-      totalUnique: 1,
-      uniquenessRatio: 1 / 1,
-    },
-    complexity: {
-      min: 1,
-      max: 1,
-      mean: 1,
-      mode: 1,
-      range: 0,
-      sum: 1,
-      total: 1,
-      totalUnique: 1,
-      unique: { 1: 1 },
-      uniquenessRatio: 1,
-      items: [1],
-    },
-    id: {
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-      ratio: 0,
-    },
-    pseudoClasses: {
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-    },
-    accessibility: {
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-      ratio: 0,
-    },
-    keyframes: {
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-    },
-    prefixed: {
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-      ratio: 0,
-    },
-    combinators: {
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-    },
-    nesting: {
-      min: 0,
-      max: 0,
-      mean: 0,
-      mode: 0,
-      range: 0,
-      sum: 0,
-      items: [0],
-      total: 1,
-      totalUnique: 1,
-      unique: {
-        0: 1,
-      },
-      uniquenessRatio: 1 / 1,
-    },
-  }
-  assert.equal(actual, expected)
-})
-
-Selectors('analyzes vendor prefixed selectors', () => {
-  let actual = analyze(`
-    input[type=text]::-webkit-input-placeholder {
-        color: green;
-    }
-    input[type=text]::-moz-placeholder {
-        color: green;
-    }
-    input[type=text]:-ms-input-placeholder {
-        color: green;
-    }
-    input[type=text]:-moz-placeholder {
-      color: green;
-    }
-
-    no-prefix,
-    fake-webkit,
-    ::-webkit-scrollbar,
-    .site-header .main-nav:hover>ul>li:nth-child(1) svg,
-    :-moz-any(header, footer) {}
-  `).selectors.prefixed
-
-  assert.is(actual.total, 6)
-  assert.is(actual.totalUnique, 6)
-  assert.equal(actual.unique, {
-    'input[type=text]::-webkit-input-placeholder': 1,
-    'input[type=text]:-ms-input-placeholder': 1,
-    '::-webkit-scrollbar': 1,
-    ':-moz-any(header, footer)': 1,
-    'input[type=text]::-moz-placeholder': 1,
-    'input[type=text]:-moz-placeholder': 1,
-  })
-})
-
-Selectors('counts combinators', () => {
-  let result = analyze(`
-    a,
-    a b,
-    a > b,
-    a ~ b,
-    a + b,
-    a    b,
-    a + b c > d e ~ f,
-    :is(a + b, a, e > f) {
-    }
-  `)
-  let actual = result.selectors.combinators
-
-  assert.is(actual.total, 12)
-  assert.is(actual.totalUnique, 4)
-  assert.is(actual.uniquenessRatio, 4 / 12)
-  assert.equal(actual.unique, {
-    ' ': 4,
-    '>': 3,
-    '~': 2,
-    '+': 3
-  })
-})
-
-Selectors('tracks combinator locations', () => {
-  let css = `
-    a b,
-    a > b,
-    a
-      b,
-    a:not(b) c,
-    a[attr] b {}
-  `
-  let result = analyze(css, {
-    useLocations: true
-  })
-  let actual = result.selectors.combinators
-
-  assert.equal(actual.uniqueWithLocations, {
-    ' ': [
-      {
-        line: 2,
-        column: 6,
-        offset: 6,
-        length: 1,
-      },
-      {
-        line: 4,
-        column: 6,
-        offset: 26,
-        length: 1,
-      },
-      {
-        line: 6,
-        column: 13,
-        offset: 48,
-        length: 1,
-      },
-      {
-        line: 7,
-        column: 12,
-        offset: 63,
-        length: 1,
-      }
-    ],
-    '>': [
-      {
-        line: 3,
-        column: 7,
-        offset: 16,
-        length: 1,
-      }
-    ]
-  })
-
-  let as_strings = actual.uniqueWithLocations[' ']
-    .map(loc => css.substring(loc.offset, loc.offset + loc.length))
-  assert.equal(as_strings, [
-    ' ',
-    `\n`,
-    ' ',
-    ' '
-  ])
-})
-
-Selectors('tracks nesting depth', () => {
-  const fixture = `
-    a {
-      color: red;
-    }
-
-    b {
-      color: green;
-
-      &:hover {
-        color: blue;
-      }
-
-      color: deepskyblue;
-
-      @container (width > 400px) {
-        color: rebeccapurple
-      }
-    }
-
-    @media print {
-      @supports (display: grid) {
-        c {
-          color: orange;
-        }
-      }
-    }
-  `
-  const actual = analyze(fixture).selectors.nesting
-  const expected = {
-    min: 0,
-    max: 2,
-    mean: 0.75,
-    mode: 0,
-    range: 2,
-    sum: 3,
-    items: [0, 0, 1, 2],
-    total: 4,
-    totalUnique: 3,
-    unique: {
-      0: 2,
-      1: 1,
-      2: 1,
-    },
-    uniquenessRatio: 3 / 4,
-  }
-  assert.equal(actual, expected)
-})
-
-Selectors('Can keep track of selector locations if we ask it to do so', () => {
-  const fixture = `
-    rule {
-      color: green;
-    }
-
-    @media print {
-      @media (min-width: 1000px) {
-        @supports (display: grid) {
-          another-rule {
-            color: purple;
-          }
-        }
-      }
-    }
-  `
-  let actual = analyze(fixture, { useLocations: true }).selectors.complexity.uniqueWithLocations
-  let expected = {
-    '1': [
-      {
-        line: 2,
-        column: 5,
-        offset: 5,
-        length: 4,
-      },
-      {
-        line: 9,
-        column: 11,
-        offset: 139,
-        length: 12,
-      }
-    ]
-  }
-
-  assert.equal(actual, expected)
-})
-
-Selectors.run()
\ No newline at end of file
diff --git a/src/selectors/selectors.test.ts b/src/selectors/selectors.test.ts
new file mode 100644
index 00000000..034dece3
--- /dev/null
+++ b/src/selectors/selectors.test.ts
@@ -0,0 +1,581 @@
+import { test, expect } from 'vitest'
+import { analyze } from '../index.js'
+
+test('are analyzed', () => {
+	const fixture = `
+    rule {
+      color: green;
+    }
+
+    @media print {
+      @media (min-width: 1000px) {
+        @supports (display: grid) {
+          another-rule {
+            color: purple;
+          }
+        }
+      }
+    }
+  `
+	const actual = analyze(fixture).selectors
+
+	expect(actual.total).toBe(2)
+	expect(actual.totalUnique).toBe(2)
+})
+
+test('handles CSS without selectors', () => {
+	const fixture = `
+    @font-face {
+      font-family: url('/test');
+      font-family: test;
+    }
+  `
+	const actual = analyze(fixture).selectors
+	const expected = {
+		total: 0,
+		totalUnique: 0,
+		uniquenessRatio: 0,
+		specificity: {
+			sum: [0, 0, 0],
+			min: [0, 0, 0],
+			max: [0, 0, 0],
+			mean: [0, 0, 0],
+			mode: [0, 0, 0],
+			items: [],
+			unique: {},
+			total: 0,
+			totalUnique: 0,
+			uniquenessRatio: 0,
+		},
+		complexity: {
+			min: 0,
+			max: 0,
+			mean: 0,
+			mode: 0,
+			range: 0,
+			sum: 0,
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+			items: [],
+		},
+		id: {
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+			ratio: 0,
+		},
+		pseudoClasses: {
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+		},
+		accessibility: {
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+			ratio: 0,
+		},
+		keyframes: {
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+		},
+		prefixed: {
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+			ratio: 0,
+		},
+		combinators: {
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+		},
+		nesting: {
+			min: 0,
+			max: 0,
+			mean: 0,
+			mode: 0,
+			range: 0,
+			sum: 0,
+			items: [],
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+		},
+	}
+	expect(actual).toEqual(expected)
+})
+
+test('have their complexity calculated', () => {
+	const fixture = `
+    rule {
+      color: green;
+    }
+
+    @media print {
+      @media (min-width: 1000px) {
+        @supports (display: grid) {
+          another-rule {
+            color: purple;
+          }
+        }
+      }
+    }
+  `
+	const actual = analyze(fixture).selectors.complexity.items
+	const expected = [1, 1]
+
+	expect(actual).toEqual(expected)
+})
+
+test('have their specificity calculated', () => {
+	const fixture = `
+    rule {
+      color: green;
+    }
+
+    * {
+      color: brown;
+    }
+
+    @media print {
+      @media (min-width: 1000px) {
+        @supports (display: grid) {
+          another-rule {
+            color: purple;
+          }
+        }
+      }
+    }
+  `
+	const actual = analyze(fixture)
+	const expected = [
+		[0, 0, 1],
+		[0, 0, 0],
+		[0, 0, 1],
+	]
+
+	expect(actual.selectors.specificity.items).toEqual(expected)
+	expect(actual.selectors.total).toEqual(3)
+})
+
+test('calculates selector uniqueness', () => {
+	const fixture = `
+    a {}
+    b {}
+
+    @media print {
+      b {}
+      c {}
+    }
+  `
+	const actual = analyze(fixture).selectors
+
+	expect(actual.total).toBe(4)
+	expect(actual.totalUnique).toBe(3)
+	expect(actual.uniquenessRatio).toBe(3 / 4)
+})
+
+test('counts <keyframes-selector>s', () => {
+	const fixture = `
+    myElement1 {
+      opacity: 1;
+    }
+
+    @keyframes test1 {
+      from {
+        opacity: 1;
+      }
+      50% {
+        opacity: 0;
+      }
+      to {
+        opacity: 1;
+      }
+    }
+
+    @media only screen {
+      myElement2 {
+        opacity: 1;
+      }
+
+      @keyframes test2 {
+        from {
+          opacity: 0.1;
+        }
+      }
+    }
+  `
+	const actual = analyze(fixture).selectors
+	expect(actual.total).toBe(2)
+	expect(actual.keyframes).toEqual({
+		total: 4,
+		totalUnique: 3,
+		unique: {
+			from: 2,
+			to: 1,
+			'50%': 1,
+		},
+		uniquenessRatio: 3 / 4,
+	})
+})
+
+test('counts ID selectors', () => {
+	const fixture = `
+    #myId,
+    #myId,
+    element#id,
+    #multiple #ids { }
+
+    /* Not an ID */
+    [href="#hash"] { }
+  `
+	const actual = analyze(fixture).selectors.id
+	const expected = {
+		total: 4,
+		totalUnique: 3,
+		unique: {
+			'#myId': 2,
+			'element#id': 1,
+			'#multiple #ids': 1,
+		},
+		uniquenessRatio: 3 / 4,
+		ratio: 4 / 5,
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('counts Accessibility selectors', () => {
+	const fixture = `
+    [aria-hidden],
+    img[role="presentation"],
+    .selector:not([role="tablist"]),
+    body.intent-mouse·[role=tabpanel][tabindex="0"]:focus,
+
+    /* false positives */
+    img[loading="lazy"],
+    [hidden] {}
+  `
+	const actual = analyze(fixture).selectors.accessibility
+	const expected = {
+		total: 4,
+		totalUnique: 4,
+		unique: {
+			'[aria-hidden]': 1,
+			'img[role="presentation"]': 1,
+			'.selector:not([role="tablist"])': 1,
+			'body.intent-mouse·[role=tabpanel][tabindex="0"]:focus': 1,
+		},
+		uniquenessRatio: 1 / 1,
+		ratio: 4 / 6,
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('handles emoji selectors', () => {
+	const fixture = `
+    .💩 {}
+  `
+	const result = analyze(fixture)
+	const actual = result.selectors
+
+	const expected = {
+		total: 1,
+		totalUnique: 1,
+		uniquenessRatio: 1,
+		specificity: {
+			sum: [0, 1, 0],
+			min: [0, 1, 0],
+			max: [0, 1, 0],
+			mean: [0, 1, 0],
+			mode: [0, 1, 0],
+			items: [[0, 1, 0]],
+			unique: {
+				'0,1,0': 1,
+			},
+			total: 1,
+			totalUnique: 1,
+			uniquenessRatio: 1 / 1,
+		},
+		complexity: {
+			min: 1,
+			max: 1,
+			mean: 1,
+			mode: 1,
+			range: 0,
+			sum: 1,
+			total: 1,
+			totalUnique: 1,
+			unique: { 1: 1 },
+			uniquenessRatio: 1,
+			items: [1],
+		},
+		id: {
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+			ratio: 0,
+		},
+		pseudoClasses: {
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+		},
+		accessibility: {
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+			ratio: 0,
+		},
+		keyframes: {
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+		},
+		prefixed: {
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+			ratio: 0,
+		},
+		combinators: {
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+		},
+		nesting: {
+			min: 0,
+			max: 0,
+			mean: 0,
+			mode: 0,
+			range: 0,
+			sum: 0,
+			items: [0],
+			total: 1,
+			totalUnique: 1,
+			unique: {
+				0: 1,
+			},
+			uniquenessRatio: 1 / 1,
+		},
+	}
+	expect(actual).toEqual(expected)
+})
+
+test('analyzes vendor prefixed selectors', () => {
+	let actual = analyze(`
+    input[type=text]::-webkit-input-placeholder {
+        color: green;
+    }
+    input[type=text]::-moz-placeholder {
+        color: green;
+    }
+    input[type=text]:-ms-input-placeholder {
+        color: green;
+    }
+    input[type=text]:-moz-placeholder {
+      color: green;
+    }
+
+    no-prefix,
+    fake-webkit,
+    ::-webkit-scrollbar,
+    .site-header .main-nav:hover>ul>li:nth-child(1) svg,
+    :-moz-any(header, footer) {}
+  `).selectors.prefixed
+
+	expect(actual.total).toBe(6)
+	expect(actual.totalUnique).toBe(6)
+	expect(actual.unique).toEqual({
+		'input[type=text]::-webkit-input-placeholder': 1,
+		'input[type=text]:-ms-input-placeholder': 1,
+		'::-webkit-scrollbar': 1,
+		':-moz-any(header, footer)': 1,
+		'input[type=text]::-moz-placeholder': 1,
+		'input[type=text]:-moz-placeholder': 1,
+	})
+})
+
+test('counts combinators', () => {
+	let result = analyze(`
+    a,
+    a b,
+    a > b,
+    a ~ b,
+    a + b,
+    a    b,
+    a + b c > d e ~ f,
+    :is(a + b, a, e > f) {
+    }
+  `)
+	let actual = result.selectors.combinators
+
+	expect(actual.total).toBe(12)
+	expect(actual.totalUnique).toBe(4)
+	expect(actual.uniquenessRatio).toBe(4 / 12)
+	expect(actual.unique).toEqual({
+		' ': 4,
+		'>': 3,
+		'~': 2,
+		'+': 3,
+	})
+})
+
+test('tracks combinator locations', () => {
+	let css = `
+    a b,
+    a > b,
+    a
+      b,
+    a:not(b) c,
+    a[attr] b {}
+  `
+	let result = analyze(css, {
+		useLocations: true,
+	})
+	let actual = result.selectors.combinators
+
+	expect(actual.uniqueWithLocations).toEqual({
+		' ': [
+			{
+				line: 2,
+				column: 6,
+				offset: 6,
+				length: 1,
+			},
+			{
+				line: 4,
+				column: 6,
+				offset: 26,
+				length: 1,
+			},
+			{
+				line: 6,
+				column: 13,
+				offset: 48,
+				length: 1,
+			},
+			{
+				line: 7,
+				column: 12,
+				offset: 63,
+				length: 1,
+			},
+		],
+		'>': [
+			{
+				line: 3,
+				column: 7,
+				offset: 16,
+				length: 1,
+			},
+		],
+	})
+
+	let as_strings = actual.uniqueWithLocations![' '].map((loc) => css.substring(loc.offset, loc.offset + loc.length))
+	expect(as_strings).toEqual([' ', `\n`, ' ', ' '])
+})
+
+test('tracks nesting depth', () => {
+	const fixture = `
+    a {
+      color: red;
+    }
+
+    b {
+      color: green;
+
+      &:hover {
+        color: blue;
+      }
+
+      color: deepskyblue;
+
+      @container (width > 400px) {
+        color: rebeccapurple
+      }
+    }
+
+    @media print {
+      @supports (display: grid) {
+        c {
+          color: orange;
+        }
+      }
+    }
+  `
+	const actual = analyze(fixture).selectors.nesting
+	const expected = {
+		min: 0,
+		max: 2,
+		mean: 0.75,
+		mode: 0,
+		range: 2,
+		sum: 3,
+		items: [0, 0, 1, 2],
+		total: 4,
+		totalUnique: 3,
+		unique: {
+			0: 2,
+			1: 1,
+			2: 1,
+		},
+		uniquenessRatio: 3 / 4,
+	}
+	expect(actual).toEqual(expected)
+})
+
+test('Can keep track of selector locations if we ask it to do so', () => {
+	const fixture = `
+    rule {
+      color: green;
+    }
+
+    @media print {
+      @media (min-width: 1000px) {
+        @supports (display: grid) {
+          another-rule {
+            color: purple;
+          }
+        }
+      }
+    }
+  `
+	let actual = analyze(fixture, { useLocations: true }).selectors.complexity.uniqueWithLocations
+	let expected = {
+		'1': [
+			{
+				line: 2,
+				column: 5,
+				offset: 5,
+				length: 4,
+			},
+			{
+				line: 9,
+				column: 11,
+				offset: 139,
+				length: 12,
+			},
+		],
+	}
+
+	expect(actual).toEqual(expected)
+})
diff --git a/src/selectors/specificity.test.js b/src/selectors/specificity.test.ts
similarity index 76%
rename from src/selectors/specificity.test.js
rename to src/selectors/specificity.test.ts
index e51acb36..1f39daff 100644
--- a/src/selectors/specificity.test.js
+++ b/src/selectors/specificity.test.ts
@@ -1,10 +1,7 @@
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
+import { test, expect } from 'vitest'
 import { analyze } from '../index.js'
 
-const Specificity = suite('Specificity')
-
-Specificity('handles the universal selector', () => {
+test('handles the universal selector', () => {
   const fixture = `
     * {}
   test * {}
@@ -14,10 +11,10 @@ Specificity('handles the universal selector', () => {
     [0, 0, 0],
     [0, 0, 1],
   ]
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-Specificity('handles ID selectors', () => {
+test('handles ID selectors', () => {
   const fixture = `
     #id,
     .Foo > .Bar ~ .Baz [type="text"] + span::before #bazz #fizz #buzz #brick #house,
@@ -36,10 +33,10 @@ Specificity('handles ID selectors', () => {
     [1, 0, 0],
     [1, 0, 1],
   ]
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-Specificity('handles class selectors', () => {
+test('handles class selectors', () => {
   const fixture = `
     .class,
     .class.class
@@ -50,10 +47,10 @@ Specificity('handles class selectors', () => {
     [0, 1, 0],
     [0, 2, 0],
   ]
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-Specificity('handles element selectors', () => {
+test('handles element selectors', () => {
   const fixture = `
     element,
     element element
@@ -64,10 +61,10 @@ Specificity('handles element selectors', () => {
     [0, 0, 1],
     [0, 0, 2],
   ]
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-Specificity('handles the :not, :is and :has pseudo classes', () => {
+test('handles the :not, :is and :has pseudo classes', () => {
   const fixture = `
     /* https://drafts.csswg.org/selectors-4/#example-bd54871c */
     :is(em, #foo), /* [1,0,0] like an ID selector (#foo)—when matched against any of <em>, <p id=foo>, or <em id=foo>. */
@@ -85,10 +82,10 @@ Specificity('handles the :not, :is and :has pseudo classes', () => {
     [1, 0, 1],
     [1, 1, 0],
   ]
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-Specificity('handles attribute selectors', () => {
+test('handles attribute selectors', () => {
   const fixture = `
     [attribute],
     .Foo > .Bar ~ .Baz [type="text"] + span::before #bazz #fizz #buzz #brick #house,
@@ -133,10 +130,10 @@ Specificity('handles attribute selectors', () => {
     [0, 1, 0],
     [0, 1, 0],
   ]
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-Specificity('handles the :where pseudo class', () => {
+test('handles the :where pseudo class', () => {
   const fixture = `
     .qux:where(em, #foo#bar#baz) /* [0,1,0] only the .qux outside the :where() contributes to selector specificity.  */
     {}
@@ -145,10 +142,10 @@ Specificity('handles the :where pseudo class', () => {
   const expected = [
     [0, 1, 0]
   ]
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-Specificity('handles pseudo element selectors', () => {
+test('handles pseudo element selectors', () => {
   const fixture = `
     element::before,
     element:before,
@@ -173,14 +170,14 @@ Specificity('handles pseudo element selectors', () => {
     [0, 0, 2],
     [0, 1, 0]
   ]
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
 // TODO: test this whenever CSSTree contains 'native' specificity analysis
 // https://twitter.com/csstree/status/1386799196355825664
-Specificity.skip('handles multiple :where or :is parts')
+test.skip('handles multiple :where or :is parts', () => {})
 
-Specificity('calculates the lowest value', () => {
+test('calculates the lowest value', () => {
   const fixture = `
     #test,
     .me,
@@ -188,10 +185,10 @@ Specificity('calculates the lowest value', () => {
     [crazy] ~ .selector > for [no|="good"] {}
   `
   const actual = analyze(fixture).selectors.specificity.min
-  assert.equal(actual, [0, 0, 1])
+  expect(actual).toEqual([0, 0, 1])
 })
 
-Specificity('calculates the highest value', () => {
+test('calculates the highest value', () => {
   const fixture = `
     #test,
     .me,
@@ -199,10 +196,10 @@ Specificity('calculates the highest value', () => {
     [crazy] ~ .selector > for [no|="good"] {}
   `
   const actual = analyze(fixture).selectors.specificity.max
-  assert.equal(actual, [1, 0, 0])
+  expect(actual).toEqual([1, 0, 0])
 })
 
-Specificity('calculates the mean value', () => {
+test('calculates the mean value', () => {
   const fixture = `
     #test,
     .me,
@@ -210,10 +207,10 @@ Specificity('calculates the mean value', () => {
     [crazy] ~ .selector > for [no|="good"] {}
   `
   const actual = analyze(fixture).selectors.specificity.mean
-  assert.equal(actual, [.25, 1, 0.5])
+  expect(actual).toEqual([.25, 1, 0.5])
 })
 
-Specificity('calculates the mode value', () => {
+test('calculates the mode value', () => {
   const fixture = `
     #test,
     .me,
@@ -221,10 +218,10 @@ Specificity('calculates the mode value', () => {
     [crazy] ~ .selector > for [no|="good"] {}
   `
   const actual = analyze(fixture).selectors.specificity.mode
-  assert.equal(actual, [0, 0, 0.5])
+  expect(actual).toEqual([0, 0, 0.5])
 })
 
-Specificity('calculates total specificity', () => {
+test('calculates total specificity', () => {
   const fixture = `
     #test,
     .me,
@@ -232,10 +229,10 @@ Specificity('calculates total specificity', () => {
     [crazy] ~ .selector > for [no|="good"] {}
   `
   const actual = analyze(fixture).selectors.specificity.sum
-  assert.equal(actual, [1, 4, 2])
+  expect(actual).toEqual([1, 4, 2])
 })
 
-Specificity('calculates specificity uniqueness', () => {
+test('calculates specificity uniqueness', () => {
   const fixture = `
     *,
     * + *,
@@ -252,15 +249,13 @@ Specificity('calculates specificity uniqueness', () => {
   `
   const actual = analyze(fixture).selectors.specificity
 
-  assert.equal(actual.unique, {
+  expect(actual.unique).toEqual({
     '0,0,0': 3,
     '0,0,1': 1,
     '0,0,2': 4,
     '1,0,0': 1,
     '0,1,0': 3,
   })
-  assert.is(actual.totalUnique, 5)
-  assert.is(actual.uniquenessRatio, 5 / 12)
-})
-
-Specificity.run()
\ No newline at end of file
+  expect(actual.totalUnique).toBe(5)
+  expect(actual.uniquenessRatio).toBe(5 / 12)
+})
\ No newline at end of file
diff --git a/src/selectors/utils.js b/src/selectors/utils.js
deleted file mode 100644
index 965f8268..00000000
--- a/src/selectors/utils.js
+++ /dev/null
@@ -1,213 +0,0 @@
-// @ts-expect-error CSS Tree types are incomplete
-import walk from 'css-tree/walker'
-import { startsWith, strEquals } from '../string-utils.js'
-import { hasVendorPrefix } from '../vendor-prefix.js'
-import { KeywordSet } from '../keyword-set.js'
-import {
-  PseudoClassSelector,
-  PseudoElementSelector,
-  TypeSelector,
-  Combinator,
-  Selector,
-  AttributeSelector,
-  Nth,
-} from '../css-tree-node-types.js'
-
-/**
- *
- * @param {import('css-tree').SelectorList} selectorListAst
- * @returns {Selector[]} Analyzed selectors in the selectorList
- */
-function analyzeList(selectorListAst, cb) {
-  let childSelectors = []
-  walk(selectorListAst, {
-    visit: Selector,
-    enter: function (node) {
-      childSelectors.push(cb(node))
-    }
-  })
-
-  return childSelectors
-}
-
-const PSEUDO_FUNCTIONS = new KeywordSet([
-  'nth-child',
-  'where',
-  'not',
-  'is',
-  'has',
-  'nth-last-child',
-  'matches',
-  '-webkit-any',
-  '-moz-any',
-])
-
-/** @param {import('css-tree').Selector} selector */
-export function isAccessibility(selector) {
-  let isA11y = false
-
-  walk(selector, function (node) {
-    if (node.type === AttributeSelector) {
-      let name = node.name.name
-      if (strEquals('role', name) || startsWith('aria-', name)) {
-        isA11y = true
-        return this.break
-      }
-    }
-    // Test for [aria-] or [role] inside :is()/:where() and friends
-    else if (node.type === PseudoClassSelector && PSEUDO_FUNCTIONS.has(node.name)) {
-      let list = analyzeList(node, isAccessibility)
-
-      for (let c of list) {
-        if (c === true) {
-          isA11y = true
-          break
-        }
-      }
-
-      return this.skip
-    }
-  })
-
-  return isA11y;
-}
-
-/**
- * @param {import('css-tree').Selector} selector
- * @returns {boolean} Whether the selector contains a vendor prefix
- */
-export function isPrefixed(selector) {
-  let isPrefixed = false
-
-  walk(selector, function (node) {
-    let type = node.type
-
-    if (type === PseudoElementSelector
-      || type === TypeSelector
-      || type === PseudoClassSelector
-    ) {
-      if (hasVendorPrefix(node.name)) {
-        isPrefixed = true
-        return this.break
-      }
-    }
-  })
-
-  return isPrefixed;
-}
-
-/**
- * @param {import('css-tree').Selector} selector
- * @returns {string[] | false} The pseudo-class name if it exists, otherwise false
- */
-export function hasPseudoClass(selector) {
-  let pseudos = []
-
-  walk(selector, function (node) {
-    if (node.type === PseudoClassSelector) {
-      pseudos.push(node.name)
-    }
-  })
-
-  if (pseudos.length === 0) {
-    return false
-  }
-
-  return pseudos;
-}
-
-/**
- * Get the Complexity for the AST of a Selector Node
- * @param {import('css-tree').Selector} selector - AST Node for a Selector
- * @return {number} - The numeric complexity of the Selector and whether it's prefixed or not
- */
-export function getComplexity(selector) {
-  let complexity = 0
-
-  walk(selector, function (node) {
-    let type = node.type
-    if (type === Selector || type === Nth) return
-
-    complexity++
-
-    if (type === PseudoElementSelector
-      || type === TypeSelector
-      || type === PseudoClassSelector
-    ) {
-      if (hasVendorPrefix(node.name)) {
-        complexity++
-      }
-    }
-
-    if (type === AttributeSelector) {
-      if (node.value) {
-        complexity++
-      }
-      return this.skip
-    }
-
-    if (type === PseudoClassSelector) {
-      if (PSEUDO_FUNCTIONS.has(node.name)) {
-        let list = analyzeList(node, getComplexity)
-
-        // Bail out for empty/non-existent :nth-child() params
-        if (list.length === 0) return
-
-        for (let c of list) {
-          complexity += c
-        }
-        return this.skip
-      }
-    }
-  })
-
-  return complexity
-}
-
-/**
- * Walk a selector node and trigger a callback every time a Combinator was found
- * We need create the `loc` for descendant combinators manually, because CSSTree
- * does not keep track of whitespace for us. We'll assume that the combinator is
- * alwas a single ` ` (space) character, even though there could be newlines or
- * multiple spaces
- * @param {import('css-tree').CssNode} node
- * @param {*} onMatch
- */
-export function getCombinators(node, onMatch) {
-  walk(node, function (
-    /** @type {import('css-tree').CssNode} */ selectorNode,
-    /** @type {import('css-tree').ListItem} */ item
-  ) {
-    if (selectorNode.type === Combinator) {
-      let loc = selectorNode.loc
-      let name = selectorNode.name
-
-      // .loc is null when selectorNode.name === ' '
-      if (loc === null) {
-        let previousLoc = item.prev.data.loc.end
-        let start = {
-          offset: previousLoc.offset,
-          line: previousLoc.line,
-          column: previousLoc.column
-        }
-
-        onMatch({
-          name,
-          loc: {
-            start,
-            end: {
-              offset: start.offset + 1,
-              line: start.line,
-              column: start.column + 1
-            }
-          }
-        })
-      } else {
-        onMatch({
-          name,
-          loc
-        })
-      }
-    }
-  })
-}
diff --git a/src/selectors/utils.ts b/src/selectors/utils.ts
new file mode 100644
index 00000000..5045f746
--- /dev/null
+++ b/src/selectors/utils.ts
@@ -0,0 +1,194 @@
+// @ts-expect-error CSS Tree types are incomplete
+import walk from 'css-tree/walker'
+import { startsWith, strEquals } from '../string-utils.js'
+import { hasVendorPrefix } from '../vendor-prefix.js'
+import { KeywordSet } from '../keyword-set.js'
+import { Combinator, Nth } from '../css-tree-node-types.js'
+import type {
+	AttributeSelector,
+	CssLocation,
+	CssNode,
+	ListItem,
+	PseudoClassSelector,
+	PseudoElementSelector,
+	Selector,
+	TypeSelector,
+} from 'css-tree'
+
+/**
+ * @returns Analyzed selectors in the selectorList
+ */
+function analyzeList(selectorListAst: Selector | PseudoClassSelector, cb: (node: Selector) => unknown): Selector[] {
+	let childSelectors: Selector[] = []
+	walk(selectorListAst, {
+		visit: 'Selector',
+		enter: function (node: Selector) {
+			// @ts-expect-error TODO: fix this
+			childSelectors.push(cb(node))
+		},
+	})
+
+	return childSelectors
+}
+
+const PSEUDO_FUNCTIONS = new KeywordSet(['nth-child', 'where', 'not', 'is', 'has', 'nth-last-child', 'matches', '-webkit-any', '-moz-any'])
+
+export function isAccessibility(selector: Selector | PseudoClassSelector): boolean {
+	let isA11y = false
+
+	walk(selector, function (node: CssNode) {
+		if (node.type === 'AttributeSelector') {
+			let name = node.name.name
+			if (strEquals('role', name) || startsWith('aria-', name)) {
+				isA11y = true
+				return walk.break
+			}
+		}
+		// Test for [aria-] or [role] inside :is()/:where() and friends
+		else if (node.type === 'PseudoClassSelector' && PSEUDO_FUNCTIONS.has(node.name)) {
+			let list = analyzeList(node, isAccessibility)
+
+			for (let c of list) {
+				// @ts-expect-error TODO: fix this
+				if (c === true) {
+					isA11y = true
+					break
+				}
+			}
+
+			return walk.skip
+		}
+	})
+
+	return isA11y
+}
+
+/**
+ * @returns true if the selector contains a vendor prefix
+ */
+export function isPrefixed(selector: Selector): boolean {
+	let isPrefixed = false
+
+	walk(selector, function (node: PseudoElementSelector | PseudoClassSelector | TypeSelector) {
+		let type = node.type
+
+		if (type === 'PseudoElementSelector' || type === 'TypeSelector' || type === 'PseudoClassSelector') {
+			if (hasVendorPrefix(node.name)) {
+				isPrefixed = true
+				return walk.break
+			}
+		}
+	})
+
+	return isPrefixed
+}
+
+/**
+ * @returns {string[] | false} The pseudo-class name if it exists, otherwise false
+ */
+export function hasPseudoClass(selector: Selector): string[] | false {
+	let pseudos: string[] = []
+
+	walk(selector, function (node: CssNode) {
+		if (node.type === 'PseudoClassSelector') {
+			pseudos.push(node.name)
+		}
+	})
+
+	if (pseudos.length === 0) {
+		return false
+	}
+
+	return pseudos
+}
+
+/**
+ * Get the Complexity for the AST of a Selector Node
+ * @param selector - AST Node for a Selector
+ * @return The numeric complexity of the Selector and whether it's prefixed or not
+ */
+export function getComplexity(selector: Selector): number {
+	let complexity = 0
+
+	walk(selector, function (node: CssNode) {
+		let type = node.type
+		if (type === 'Selector' || type === Nth) return
+
+		complexity++
+
+		if (type === 'PseudoElementSelector' || type === 'TypeSelector' || type === 'PseudoClassSelector') {
+			if (hasVendorPrefix((node as PseudoElementSelector | TypeSelector | PseudoClassSelector).name)) {
+				complexity++
+			}
+		}
+
+		if (type === 'AttributeSelector') {
+			if ((node as AttributeSelector).value) {
+				complexity++
+			}
+			return walk.skip
+		}
+
+		if (type === 'PseudoClassSelector') {
+			if (PSEUDO_FUNCTIONS.has((node as PseudoClassSelector).name)) {
+				let list = analyzeList(node as PseudoClassSelector, getComplexity)
+
+				// Bail out for empty/non-existent :nth-child() params
+				if (list.length === 0) return
+
+				for (let c of list) {
+					// @ts-expect-error TODO: fix this
+					complexity += c
+				}
+				return walk.skip
+			}
+		}
+	})
+
+	return complexity
+}
+
+/**
+ * Walk a selector node and trigger a callback every time a Combinator was found
+ * We need create the `loc` for descendant combinators manually, because CSSTree
+ * does not keep track of whitespace for us. We'll assume that the combinator is
+ * alwas a single ` ` (space) character, even though there could be newlines or
+ * multiple spaces
+ */
+export function getCombinators(node: CssNode, onMatch: ({ name, loc }: { name: string; loc: CssLocation }) => void) {
+	walk(node, function (selectorNode: CssNode, item: ListItem<CssNode>) {
+		if (selectorNode.type === Combinator) {
+			let loc = selectorNode.loc
+			let name = selectorNode.name
+
+			// .loc is null when selectorNode.name === ' '
+			if (loc === null) {
+				let previousLoc = item.prev!.data.loc!.end
+				let start = {
+					offset: previousLoc.offset,
+					line: previousLoc.line,
+					column: previousLoc.column,
+				}
+
+				onMatch({
+					name,
+					// @ts-expect-error TODO: fix this
+					loc: {
+						start,
+						end: {
+							offset: start.offset + 1,
+							line: start.line,
+							column: start.column + 1,
+						},
+					},
+				})
+			} else {
+				onMatch({
+					name,
+					// @ts-expect-error TODO: fix this
+					loc,
+				})
+			}
+		}
+	})
+}
diff --git a/src/string-utils.js b/src/string-utils.js
deleted file mode 100644
index 53e39f57..00000000
--- a/src/string-utils.js
+++ /dev/null
@@ -1,99 +0,0 @@
-/**
- * Case-insensitive compare two character codes
- * @param {string} referenceCode
- * @param {string} testCode
- * @see https://github.com/csstree/csstree/blob/41f276e8862d8223eeaa01a3d113ab70bb13d2d9/lib/tokenizer/utils.js#L22
- */
-function compareChar(referenceCode, testCode) {
-  // if uppercase
-  if (testCode >= 0x0041 && testCode <= 0x005A) {
-    // shifting the 6th bit makes a letter lowercase
-    testCode = testCode | 32
-  }
-  return referenceCode === testCode
-}
-
-/**
- * Case-insensitive string-comparison
- * @example
- * strEquals('test', 'test') // true
- * strEquals('test', 'TEST') // true
- * strEquals('test', 'TesT') // true
- * strEquals('test', 'derp') // false
- *
- * @param {string} base The string to check against
- * @param {string} maybe The test string, possibly containing uppercased characters
- * @returns {boolean} true if the two strings are the same, false otherwise
- */
-export function strEquals(base, maybe) {
-  if (base === maybe) return true
-
-  let len = base.length;
-  if (len !== maybe.length) return false
-
-
-  for (let i = 0; i < len; i++) {
-    if (compareChar(base.charCodeAt(i), maybe.charCodeAt(i)) === false) {
-      return false
-    }
-  }
-
-  return true
-}
-
-/**
- * Case-insensitive testing whether a string ends with a given substring
- *
- * @example
- * endsWith('test', 'my-test') // true
- * endsWith('test', 'est') // false
- *
- * @param {string} base e.g. '-webkit-transform'
- * @param {string} maybe e.g. 'transform'
- * @returns {boolean} true if `test` ends with `base`, false otherwise
- */
-export function endsWith(base, maybe) {
-  if (base === maybe) return true
-
-  let len = maybe.length
-  let offset = len - base.length
-
-  if (offset < 0) {
-    return false
-  }
-
-  for (let i = len - 1; i >= offset; i--) {
-    if (compareChar(base.charCodeAt(i - offset), maybe.charCodeAt(i)) === false) {
-      return false
-    }
-  }
-
-  return true
-}
-
-/**
- * Case-insensitive testing whether a string starts with a given substring
- *
- * @example
- * startsWith('test', 'my-test') // false
- * startsWith('test', 'tes') // true
- * startsWith('test', 'test-me') // true
- *
- * @param {string} base
- * @param {string} maybe
- * @returns {boolean} true if `base` starts with `maybe`, false otherwise
- */
-export function startsWith(base, maybe) {
-  if (base === maybe) return true
-
-  let len = base.length
-  if (maybe.length < len) return false
-
-  for (let i = 0; i < len; i++) {
-    if (compareChar(base.charCodeAt(i), maybe.charCodeAt(i)) === false) {
-      return false
-    }
-  }
-
-  return true
-}
diff --git a/src/string-utils.test.js b/src/string-utils.test.js
deleted file mode 100644
index 73d2b74a..00000000
--- a/src/string-utils.test.js
+++ /dev/null
@@ -1,41 +0,0 @@
-import { suite } from 'uvu';
-import * as assert from 'uvu/assert';
-import { strEquals, endsWith, startsWith } from './string-utils.js'
-
-const StringUtils = suite('Public API')
-
-StringUtils('strEquals', () => {
-  assert.ok(strEquals('keyframes', 'keyframes'))
-  assert.ok(strEquals('blue', 'BLUE'))
-  assert.ok(strEquals('test-me', 'TEST-me'))
-
-  assert.not.ok(strEquals('-webkit-keyframes', 'keyframes'))
-  assert.not.ok(strEquals('abc', 'abcd'))
-  assert.not.ok(strEquals('abc', ''))
-})
-
-StringUtils('endsWith', () => {
-  assert.ok(endsWith('keyframes', 'keyframes'))
-  assert.ok(endsWith('keyframes', '-webkit-keyframes'))
-  assert.ok(endsWith('keyframes', 'testkeyframes'))
-  assert.ok(endsWith('keyframes', 'testKeyframes'))
-  assert.ok(endsWith('test', 'test'))
-
-  assert.not.ok(endsWith('keyframes', ''))
-  assert.not.ok(endsWith('keyframes', 'test'))
-  assert.not.ok(endsWith('keyframes', 'eyframes'))
-})
-
-StringUtils('startsWith', () => {
-  assert.ok(startsWith('data:', 'data:<xml>'))
-  assert.ok(startsWith('animation', 'animation'))
-  assert.ok(startsWith('animation', 'animation-duration'))
-  assert.ok(startsWith('animation', 'Animation'))
-  assert.ok(startsWith('test', 'test'))
-
-  assert.not.ok(startsWith('data:', 'nope'))
-  assert.not.ok(startsWith('test', ''))
-  assert.not.ok(startsWith('test-test', 'test'))
-})
-
-StringUtils.run()
\ No newline at end of file
diff --git a/src/string-utils.test.ts b/src/string-utils.test.ts
new file mode 100644
index 00000000..d1162f18
--- /dev/null
+++ b/src/string-utils.test.ts
@@ -0,0 +1,36 @@
+import { test, expect } from 'vitest'
+import { strEquals, endsWith, startsWith } from './string-utils.js'
+
+test('strEquals', () => {
+	expect(strEquals('keyframes', 'keyframes')).toEqual(true)
+	expect(strEquals('blue', 'BLUE')).toEqual(true)
+	expect(strEquals('test-me', 'TEST-me')).toEqual(true)
+
+	expect(strEquals('-webkit-keyframes', 'keyframes')).toEqual(false)
+	expect(strEquals('abc', 'abcd')).toEqual(false)
+	expect(strEquals('abc', '')).toEqual(false)
+})
+
+test('endsWith', () => {
+	expect(endsWith('keyframes', 'keyframes')).toEqual(true)
+	expect(endsWith('keyframes', '-webkit-keyframes')).toEqual(true)
+	expect(endsWith('keyframes', 'testkeyframes')).toEqual(true)
+	expect(endsWith('keyframes', 'testKeyframes')).toEqual(true)
+	expect(endsWith('test', 'test')).toEqual(true)
+
+	expect(endsWith('keyframes', '')).toEqual(false)
+	expect(endsWith('keyframes', 'test')).toEqual(false)
+	expect(endsWith('keyframes', 'eyframes')).toEqual(false)
+})
+
+test('startsWith', () => {
+	expect(startsWith('data:', 'data:<xml>')).toEqual(true)
+	expect(startsWith('animation', 'animation')).toEqual(true)
+	expect(startsWith('animation', 'animation-duration')).toEqual(true)
+	expect(startsWith('animation', 'Animation')).toEqual(true)
+	expect(startsWith('test', 'test')).toEqual(true)
+
+	expect(startsWith('data:', 'nope')).toEqual(false)
+	expect(startsWith('test', '')).toEqual(false)
+	expect(startsWith('test-test', 'test')).toEqual(false)
+})
diff --git a/src/string-utils.ts b/src/string-utils.ts
new file mode 100644
index 00000000..ea033d21
--- /dev/null
+++ b/src/string-utils.ts
@@ -0,0 +1,94 @@
+/**
+ * Case-insensitive compare two character codes
+ * @see https://github.com/csstree/csstree/blob/41f276e8862d8223eeaa01a3d113ab70bb13d2d9/lib/tokenizer/utils.js#L22
+ */
+function compareChar(referenceCode: number, testCode: number): boolean {
+	// if uppercase
+	if (testCode >= 0x0041 && testCode <= 0x005a) {
+		// shifting the 6th bit makes a letter lowercase
+		testCode = testCode | 32
+	}
+	return referenceCode === testCode
+}
+
+/**
+ * Case-insensitive string-comparison
+ * @example
+ * strEquals('test', 'test') // true
+ * strEquals('test', 'TEST') // true
+ * strEquals('test', 'TesT') // true
+ * strEquals('test', 'derp') // false
+ *
+ * @param base The string to check against
+ * @param maybe The test string, possibly containing uppercased characters
+ * @returns true if the two strings are the same, false otherwise
+ */
+export function strEquals(base: string, maybe: string): boolean {
+	if (base === maybe) return true
+
+	let len = base.length
+	if (len !== maybe.length) return false
+
+	for (let i = 0; i < len; i++) {
+		if (compareChar(base.charCodeAt(i), maybe.charCodeAt(i)) === false) {
+			return false
+		}
+	}
+
+	return true
+}
+
+/**
+ * Case-insensitive testing whether a string ends with a given substring
+ *
+ * @example
+ * endsWith('test', 'my-test') // true
+ * endsWith('test', 'est') // false
+ *
+ * @param base e.g. '-webkit-transform'
+ * @param maybe e.g. 'transform'
+ * @returns true if `test` ends with `base`, false otherwise
+ */
+export function endsWith(base: string, maybe: string): boolean {
+	if (base === maybe) return true
+
+	let len = maybe.length
+	let offset = len - base.length
+
+	if (offset < 0) {
+		return false
+	}
+
+	for (let i = len - 1; i >= offset; i--) {
+		if (compareChar(base.charCodeAt(i - offset), maybe.charCodeAt(i)) === false) {
+			return false
+		}
+	}
+
+	return true
+}
+
+/**
+ * Case-insensitive testing whether a string starts with a given substring
+ *
+ * @example
+ * startsWith('test', 'my-test') // false
+ * startsWith('test', 'tes') // true
+ * startsWith('test', 'test-me') // true
+ *
+ * @returns true if `base` starts with `maybe`, false otherwise
+ */
+export function startsWith(base: string, maybe: string) {
+	if (base === maybe) return true
+
+	let len = base.length
+	if (maybe.length < len) return false
+
+	for (let i = 0; i < len; i++) {
+		if (compareChar(base.charCodeAt(i), maybe.charCodeAt(i)) === false) {
+			return false
+		}
+	}
+
+	return true
+}
diff --git a/src/stylesheet/stylesheet.test.js b/src/stylesheet/stylesheet.test.ts
similarity index 58%
rename from src/stylesheet/stylesheet.test.js
rename to src/stylesheet/stylesheet.test.ts
index f47b5cdb..34851b4d 100644
--- a/src/stylesheet/stylesheet.test.js
+++ b/src/stylesheet/stylesheet.test.ts
@@ -1,12 +1,9 @@
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
+import { test, expect } from 'vitest'
 import { analyze } from '../index.js'
 import { getEmbedType } from './stylesheet.js'
 
-const Stylesheet = suite('Stylesheet')
-
-Stylesheet('counts Lines of Code', () => {
-  const fixture = `
+test('counts Lines of Code', () => {
+	const fixture = `
     /* doc */
 
     html {
@@ -17,12 +14,12 @@ Stylesheet('counts Lines of Code', () => {
 
     }
   `
-  const actual = analyze(fixture).stylesheet.linesOfCode
-  assert.is(actual, 11)
+	const actual = analyze(fixture).stylesheet.linesOfCode
+	expect(actual).toBe(11)
 })
 
-Stylesheet('counts Source Lines of Code', () => {
-  const fixture = `
+test('counts Source Lines of Code', () => {
+	const fixture = `
     rule {
       color: green;
       color: orange !important;
@@ -47,18 +44,18 @@ Stylesheet('counts Source Lines of Code', () => {
       }
     }
   `
-  const actual = analyze(fixture).stylesheet.sourceLinesOfCode
-  assert.is(actual, 13)
+	const actual = analyze(fixture).stylesheet.sourceLinesOfCode
+	expect(actual).toBe(13)
 })
 
-Stylesheet('calculates filesize', () => {
-  const fixture = `test {}`
-  const actual = analyze(fixture).stylesheet.size
-  assert.is(actual, 7)
+test('calculates filesize', () => {
+	const fixture = `test {}`
+	const actual = analyze(fixture).stylesheet.size
+	expect(actual).toBe(7)
 })
 
-Stylesheet('counts comments', () => {
-  const fixture = `
+test('counts comments', () => {
+	const fixture = `
     /* comment 1 */
     test1,
     /* comment 2 */
@@ -76,18 +73,18 @@ Stylesheet('counts comments', () => {
       /* comment 6 */
     }
   `
-  const result = analyze(fixture)
-  const actual = result.stylesheet.comments
-  const expected = {
-    total: 6,
-    size: 66,
-  }
+	const result = analyze(fixture)
+	const actual = result.stylesheet.comments
+	const expected = {
+		total: 6,
+		size: 66,
+	}
 
-  assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
-Stylesheet('measures base64 contents', () => {
-  const fixture = `
+test('measures base64 contents', () => {
+	const fixture = `
     /* Demo from https://css-tricks.com/data-uris/ */
     li {
       background:
@@ -114,34 +111,34 @@ Stylesheet('measures base64 contents', () => {
     }
   `
 
-  const actual = analyze(fixture).stylesheet.embeddedContent
-  const expected = {
-    size: {
-      total: 2337,
-      ratio: 0.8266713830916166,
-    },
-    types: {
-      total: 5,
-      totalUnique: 2,
-      uniquenessRatio: 2 / 5,
-      unique: {
-        'image/gif': {
-          count: 1,
-          size: 310,
-        },
-        'image/svg+xml': {
-          count: 4,
-          size: 2027,
-        },
-      },
-    }
-  }
+	const actual = analyze(fixture).stylesheet.embeddedContent
+	const expected = {
+		size: {
+			total: 2337,
+			ratio: 0.8266713830916166,
+		},
+		types: {
+			total: 5,
+			totalUnique: 2,
+			uniquenessRatio: 2 / 5,
+			unique: {
+				'image/gif': {
+					count: 1,
+					size: 310,
+				},
+				'image/svg+xml': {
+					count: 4,
+					size: 2027,
+				},
+			},
+		},
+	}
 
-  assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
-Stylesheet('measures base64 contents - with locations', () => {
-  const fixture = `
+test('measures base64 contents - with locations', () => {
+	const fixture = `
     /* Demo from https://css-tricks.com/data-uris/ */
     li {
       background:
@@ -168,68 +165,68 @@ Stylesheet('measures base64 contents - with locations', () => {
     }
   `
 
-  const actual = analyze(fixture, { useLocations: true }).stylesheet.embeddedContent
-  const expected = {
-    size: {
-      total: 2337,
-      ratio: 0.8266713830916166,
-    },
-    types: {
-      total: 5,
-      totalUnique: 2,
-      uniquenessRatio: 2 / 5,
-      unique: {
-        'image/gif': {
-          count: 1,
-          size: 310,
-          uniqueWithLocations: [
-            {
-              line: 5,
-              column: 9,
-              offset: 90,
-              length: 315,
-            }
-          ],
-        },
-        'image/svg+xml': {
-          count: 4,
-          size: 2027,
-          uniqueWithLocations: [
-            {
-              line: 13,
-              column: 19,
-              offset: 584,
-              length: 464
-            },
-            {
-              line: 14,
-              column: 19,
-              offset: 1068,
-              length: 439
-            },
-            {
-              line: 19,
-              column: 25,
-              offset: 1594,
-              length: 862
-            },
-            {
-              line: 24,
-              column: 26,
-              offset: 2531,
-              length: 286
-            }
-          ],
-        },
-      },
-    }
-  }
+	const actual = analyze(fixture, { useLocations: true }).stylesheet.embeddedContent
+	const expected = {
+		size: {
+			total: 2337,
+			ratio: 0.8266713830916166,
+		},
+		types: {
+			total: 5,
+			totalUnique: 2,
+			uniquenessRatio: 2 / 5,
+			unique: {
+				'image/gif': {
+					count: 1,
+					size: 310,
+					uniqueWithLocations: [
+						{
+							line: 5,
+							column: 9,
+							offset: 90,
+							length: 315,
+						},
+					],
+				},
+				'image/svg+xml': {
+					count: 4,
+					size: 2027,
+					uniqueWithLocations: [
+						{
+							line: 13,
+							column: 19,
+							offset: 584,
+							length: 464,
+						},
+						{
+							line: 14,
+							column: 19,
+							offset: 1068,
+							length: 439,
+						},
+						{
+							line: 19,
+							column: 25,
+							offset: 1594,
+							length: 862,
+						},
+						{
+							line: 24,
+							column: 26,
+							offset: 2531,
+							length: 286,
+						},
+					],
+				},
+			},
+		},
+	}
 
-  assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
-Stylesheet('reports embed size correctly when there are duplicates', () => {
-  const fixture = `
+test('reports embed size correctly when there are duplicates', () => {
+	const fixture = `
     /* Demo from https://codepen.io/chriscoyier/pen/ZQgvyG/ */
     .chevron-down {
       background: url(data:image/svg+xml,%3Csvg%20id%3D%22Layer_1%22%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%20195.6%20107.8%22%3E%3Cpath%20fill%3D%22%23B5B5B5%22%20class%3D%22st0%22%20d%3D%22M97.8%20107.8c-2.6%200-5.1-1-7.1-2.9L2.9%2017.1C-1%2013.2-1%206.8%202.9%202.9%206.8-1%2013.2-1%2017.1%202.9l80.7%2080.7%2080.7-80.7c3.9-3.9%2010.2-3.9%2014.1%200%203.9%203.9%203.9%2010.2%200%2014.1l-87.8%2087.8c-1.9%202-4.4%203-7%203z%22%2F%3E%3C%2Fsvg%3E);
@@ -240,43 +237,50 @@ Stylesheet('reports embed size correctly when there are duplicates', () => {
     }
   `
 
-  const actual = analyze(fixture).stylesheet.embeddedContent
-  const expected = {
-    size: {
-      total: 918,
-      ratio: 0.8218442256042973,
-    },
-    types: {
-      total: 2,
-      totalUnique: 1,
-      uniquenessRatio: 1 / 2,
-      unique: {
-        'image/svg+xml': {
-          count: 2,
-          size: 918,
-        },
-      },
-    }
-  }
+	const actual = analyze(fixture).stylesheet.embeddedContent
+	const expected = {
+		size: {
+			total: 918,
+			ratio: 0.8218442256042973,
+		},
+		types: {
+			total: 2,
+			totalUnique: 1,
+			uniquenessRatio: 1 / 2,
+			unique: {
+				'image/svg+xml': {
+					count: 2,
+					size: 918,
+				},
+			},
+		},
+	}
 
-  assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
-Stylesheet('correctly extracts embed types', () => {
-  ;[
-    ['test', 'data:test;nothing-to-see-here'],
-    ['image/gif', 'data:image/gif;base64,R0lGODlhEAAQAMQAAORHHOVS'],
-    ['image/svg+xml', 'data:image/svg+xml,%3Csvg%20id%3D%22Layer_'],
-    ['image/svg+xml', 'data:image/svg+xml;base64,PHN2ZyBpZD0iTGF5'],
-    ['application/font-woff', 'data:application/font-woff;base64,d09GRgAB'],
-    ['font/opentype', 'data:font/opentype;base64,T1RUTwAJAIAAAw'],
-    ['image/png', 'data:image/png;base64,iVBORw0KGgoAAAANS'],
-    ['image/svg+xml', `data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 28.84 26.6'%3E%3Cdefs%3E%3Cstyle%3E.cls-1%7Bfill:%23e93e32;%7D%3C/style%3E%3C/defs%3E%3Ctitle%3EArtboard 29%3C/title%3E%3Cpath class='cls-1' d='M3.29,2.73a66.7,66.7,0,0,0,3.21,9.52l6.29,1.08L8.1,15.53c2.91,5.28,7,9.09,12.14,4.55L25,24.52l.57-.52-3.83-5.48c3.6-4.32,1.74-7.76-1.93-10.36L17,13.29l-.1-6.85A43.83,43.83,0,0,0,11,4L9,7.7,9,3.39c-2.2-.65-4.07-1.08-5.08-1.3A.52.52,0,0,0,3.29,2.73Z'/%3E%3C/svg%3E`],
-    ['image/svg+xml', `data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 28.84 26.6'%3E%3Cdefs%3E%3Cstyle%3E.cls-1%7Bfill:%23e93e32%7D%3C/style%3E%3C/defs%3E%3Crect class='cls-1' x='8.25' y='2.31' width='3.06' height='3.66' rx='1.03' ry='1.03'/%3E%3Crect class='cls-1' x='17.53' y='2.31' width='3.06' height='3.66' rx='1.03' ry='1.03'/%3E%3Cpath class='cls-1' d='M24.1 5.39h-2.56a2 2 0 01-2 1.59h-1a2 2 0 01-2-1.59h-4.28a2 2 0 01-2 1.59h-1a2 2 0 01-2-1.59H4.75a2.07 2.07 0 00-2.08 2.07v14.75a2.07 2.07 0 002.07 2.07H24.1a2.07 2.07 0 002.07-2.07V7.46a2.07 2.07 0 00-2.07-2.07zm-.29 16.15H5.23V8.45h18.58z'/%3E%3Cpath class='cls-1' d='M7.18 11.71h2.5v2.5h-2.5zM11.27 11.71h2.5v2.5h-2.5zM15.26 11.71h2.5v2.5h-2.5zM19.35 11.71h2.5v2.5h-2.5zM7.18 15.78h2.5v2.5h-2.5zM11.27 15.78h2.5v2.5h-2.5zM15.26 15.78h2.5v2.5h-2.5zM19.35 15.78h2.5v2.5h-2.5z'/%3E%3C/svg%3E`],
-    ['image/svg+xml', `data:image/svg+xml,%3Csvg width='9' height='11' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M3.55.246c.257-.329.647-.327.903 0l3.36 4.66c.256.329.256.864 0 1.192L4.45 10.75c-.257.329-.644.327-.9 0L.192 6.098c-.256-.329-.256-.865 0-1.192L3.55.246z' fill='%23fff'/%3E%3C/svg%3E`]
-  ].forEach(([expected, fixture]) => {
-    assert.is(getEmbedType(fixture), expected)
-  })
+test('correctly extracts embed types', () => {
+	;[
+		['test', 'data:test;nothing-to-see-here'],
+		['image/gif', 'data:image/gif;base64,R0lGODlhEAAQAMQAAORHHOVS'],
+		['image/svg+xml', 'data:image/svg+xml,%3Csvg%20id%3D%22Layer_'],
+		['image/svg+xml', 'data:image/svg+xml;base64,PHN2ZyBpZD0iTGF5'],
+		['application/font-woff', 'data:application/font-woff;base64,d09GRgAB'],
+		['font/opentype', 'data:font/opentype;base64,T1RUTwAJAIAAAw'],
+		['image/png', 'data:image/png;base64,iVBORw0KGgoAAAANS'],
+		[
+			'image/svg+xml',
+			`data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 28.84 26.6'%3E%3Cdefs%3E%3Cstyle%3E.cls-1%7Bfill:%23e93e32;%7D%3C/style%3E%3C/defs%3E%3Ctitle%3EArtboard 29%3C/title%3E%3Cpath class='cls-1' d='M3.29,2.73a66.7,66.7,0,0,0,3.21,9.52l6.29,1.08L8.1,15.53c2.91,5.28,7,9.09,12.14,4.55L25,24.52l.57-.52-3.83-5.48c3.6-4.32,1.74-7.76-1.93-10.36L17,13.29l-.1-6.85A43.83,43.83,0,0,0,11,4L9,7.7,9,3.39c-2.2-.65-4.07-1.08-5.08-1.3A.52.52,0,0,0,3.29,2.73Z'/%3E%3C/svg%3E`,
+		],
+		[
+			'image/svg+xml',
+			`data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 28.84 26.6'%3E%3Cdefs%3E%3Cstyle%3E.cls-1%7Bfill:%23e93e32%7D%3C/style%3E%3C/defs%3E%3Crect class='cls-1' x='8.25' y='2.31' width='3.06' height='3.66' rx='1.03' ry='1.03'/%3E%3Crect class='cls-1' x='17.53' y='2.31' width='3.06' height='3.66' rx='1.03' ry='1.03'/%3E%3Cpath class='cls-1' d='M24.1 5.39h-2.56a2 2 0 01-2 1.59h-1a2 2 0 01-2-1.59h-4.28a2 2 0 01-2 1.59h-1a2 2 0 01-2-1.59H4.75a2.07 2.07 0 00-2.08 2.07v14.75a2.07 2.07 0 002.07 2.07H24.1a2.07 2.07 0 002.07-2.07V7.46a2.07 2.07 0 00-2.07-2.07zm-.29 16.15H5.23V8.45h18.58z'/%3E%3Cpath class='cls-1' d='M7.18 11.71h2.5v2.5h-2.5zM11.27 11.71h2.5v2.5h-2.5zM15.26 11.71h2.5v2.5h-2.5zM19.35 11.71h2.5v2.5h-2.5zM7.18 15.78h2.5v2.5h-2.5zM11.27 15.78h2.5v2.5h-2.5zM15.26 15.78h2.5v2.5h-2.5zM19.35 15.78h2.5v2.5h-2.5z'/%3E%3C/svg%3E`,
+		],
+		[
+			'image/svg+xml',
+			`data:image/svg+xml,%3Csvg width='9' height='11' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M3.55.246c.257-.329.647-.327.903 0l3.36 4.66c.256.329.256.864 0 1.192L4.45 10.75c-.257.329-.644.327-.9 0L.192 6.098c-.256-.329-.256-.865 0-1.192L3.55.246z' fill='%23fff'/%3E%3C/svg%3E`,
+		],
+	].forEach(([expected, fixture]) => {
+		expect(getEmbedType(fixture)).toBe(expected)
+	})
 })
-
-Stylesheet.run()
\ No newline at end of file
diff --git a/src/stylesheet/stylesheet.js b/src/stylesheet/stylesheet.ts
similarity index 72%
rename from src/stylesheet/stylesheet.js
rename to src/stylesheet/stylesheet.ts
index a01a70db..5927943d 100644
--- a/src/stylesheet/stylesheet.js
+++ b/src/stylesheet/stylesheet.ts
@@ -1,5 +1,4 @@
-/** @param {string} embed */
-export function getEmbedType(embed) {
+export function getEmbedType(embed: string) {
 	// data:image/gif;base64,R0lG
 	let start = 5 // `data:`.length
 	let semicolon = embed.indexOf(';')
@@ -10,8 +9,8 @@ export function getEmbedType(embed) {
 	}
 
 	if (comma !== -1 && comma < semicolon) {
-		return embed.substring(start, comma);
+		return embed.substring(start, comma)
 	}
 
 	return embed.substring(start, semicolon)
-}
\ No newline at end of file
+}
diff --git a/src/values/animations.js b/src/values/animations.js
deleted file mode 100644
index 22bf328b..00000000
--- a/src/values/animations.js
+++ /dev/null
@@ -1,61 +0,0 @@
-import { KeywordSet } from "../keyword-set.js"
-import { keywords } from "./values.js"
-import {
-  Operator,
-  Dimension,
-  Identifier,
-  Func,
-} from '../css-tree-node-types.js'
-
-const TIMING_KEYWORDS = new KeywordSet([
-  'linear',
-  'ease',
-  'ease-in',
-  'ease-out',
-  'ease-in-out',
-  'step-start',
-  'step-end',
-])
-
-const TIMING_FUNCTION_VALUES = new KeywordSet([
-  'cubic-bezier',
-  'steps'
-])
-
-export function analyzeAnimation(children, cb) {
-  let durationFound = false
-
-  for (let child of children) {
-    let type = child.type
-    let name = child.name
-
-    // Right after a ',' we start over again
-    if (type === Operator) {
-      durationFound = false
-    } else if (type === Dimension && durationFound === false) {
-      // The first Dimension is the duration, the second is the delay
-      durationFound = true
-      cb({
-        type: 'duration',
-        value: child,
-      })
-    } else if (type === Identifier) {
-      if (TIMING_KEYWORDS.has(name)) {
-        cb({
-          type: 'fn',
-          value: child,
-        })
-      } else if (keywords.has(name)) {
-        cb({
-          type: 'keyword',
-          value: child,
-        })
-      }
-    } else if (type === Func && TIMING_FUNCTION_VALUES.has(name)) {
-      cb({
-        type: 'fn',
-        value: child,
-      })
-    }
-  }
-}
diff --git a/src/values/animations.test.js b/src/values/animations.test.ts
similarity index 84%
rename from src/values/animations.test.js
rename to src/values/animations.test.ts
index b2d44f5f..dbd72acb 100644
--- a/src/values/animations.test.js
+++ b/src/values/animations.test.ts
@@ -1,10 +1,8 @@
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
+import { test } from 'vitest'
+import { expect } from 'vitest'
 import { analyze } from '../index.js'
 
-const Animations = suite('Animations')
-
-Animations('finds simple durations', () => {
+test('finds simple durations', () => {
   const fixture = `
     durations {
       animation-duration: 1s;
@@ -24,10 +22,10 @@ Animations('finds simple durations', () => {
     },
     uniquenessRatio: 3 / 3
   }
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-Animations('finds duration lists', () => {
+test('finds duration lists', () => {
   const fixture = `
     durations {
       animation-duration: 1s, 1s;
@@ -45,10 +43,10 @@ Animations('finds duration lists', () => {
     },
     uniquenessRatio: 3 / 4
   }
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-Animations('finds simple timing functions', () => {
+test('finds simple timing functions', () => {
   const fixture = `
     timings {
       animation-timing-function: linear;
@@ -72,10 +70,10 @@ Animations('finds simple timing functions', () => {
     },
     uniquenessRatio: 3 / 4
   }
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-Animations('finds timing functions in value lists', () => {
+test('finds timing functions in value lists', () => {
   const fixture = `
     timings {
       animation-timing-function: ease, step-start, cubic-bezier(0.1, 0.7, 1, 0.1);
@@ -92,10 +90,10 @@ Animations('finds timing functions in value lists', () => {
     },
     uniquenessRatio: 1
   }
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-Animations('finds shorthand durations', () => {
+test('finds shorthand durations', () => {
   const fixture = `
     durations {
       animation: 1s ANIMATION_NAME linear;
@@ -122,10 +120,10 @@ Animations('finds shorthand durations', () => {
     },
     uniquenessRatio: 5 / 5
   }
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-Animations('finds shorthand timing functions', () => {
+test('finds shorthand timing functions', () => {
   const fixture = `
     durations {
       animation: 1s ANIMATION_NAME linear;
@@ -152,10 +150,10 @@ Animations('finds shorthand timing functions', () => {
     },
     uniquenessRatio: 3 / 5
   }
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-Animations('analyzes animations/transitions with value lists', () => {
+test('analyzes animations/transitions with value lists', () => {
   const fixture = `
     multi-value {
       animation: 1s ANIMATION_NAME linear, 2s ANIMATION_NAME linear;
@@ -202,7 +200,5 @@ Animations('analyzes animations/transitions with value lists', () => {
       uniquenessRatio: 5 / 8
     }
   }
-  assert.equal(actual, expected)
-})
-
-Animations.run()
\ No newline at end of file
+  expect(actual).toEqual(expected)
+})
\ No newline at end of file
diff --git a/src/values/animations.ts b/src/values/animations.ts
new file mode 100644
index 00000000..c9d30bd7
--- /dev/null
+++ b/src/values/animations.ts
@@ -0,0 +1,47 @@
+import { KeywordSet } from '../keyword-set.js'
+import { keywords } from './values.js'
+import { Operator, Dimension, Identifier, Func } from '../css-tree-node-types.js'
+import type { CssNode, List } from 'css-tree'
+
+const TIMING_KEYWORDS = new KeywordSet(['linear', 'ease', 'ease-in', 'ease-out', 'ease-in-out', 'step-start', 'step-end'])
+
+const TIMING_FUNCTION_VALUES = new KeywordSet(['cubic-bezier', 'steps'])
+
+export function analyzeAnimation(children: List<CssNode>, cb: ({ type, value }: { type: string; value: CssNode }) => void) {
+	let durationFound = false
+
+	for (let child of children) {
+		let type = child.type
+		// @ts-expect-error TODO: fix this
+		let name = child.name
+
+		// Right after a ',' we start over again
+		if (type === Operator) {
+			durationFound = false
+		} else if (type === Dimension && durationFound === false) {
+			// The first Dimension is the duration, the second is the delay
+			durationFound = true
+			cb({
+				type: 'duration',
+				value: child,
+			})
+		} else if (type === Identifier) {
+			if (TIMING_KEYWORDS.has(name)) {
+				cb({
+					type: 'fn',
+					value: child,
+				})
+			} else if (keywords.has(name)) {
+				cb({
+					type: 'keyword',
+					value: child,
+				})
+			}
+		} else if (type === Func && TIMING_FUNCTION_VALUES.has(name)) {
+			cb({
+				type: 'fn',
+				value: child,
+			})
+		}
+	}
+}
diff --git a/src/values/border-radius.test.js b/src/values/border-radius.test.ts
similarity index 94%
rename from src/values/border-radius.test.js
rename to src/values/border-radius.test.ts
index 0cfa3b86..43cac533 100644
--- a/src/values/border-radius.test.js
+++ b/src/values/border-radius.test.ts
@@ -1,9 +1,7 @@
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
+import { test } from 'vitest'
+import { expect } from 'vitest'
 import { analyze } from '../index.js'
 
-const test = suite('Border Radius')
-
 test('finds simple values', () => {
 	const fixture = `
     radius {
@@ -70,7 +68,7 @@ test('finds simple values', () => {
 		}
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
 
@@ -110,7 +108,7 @@ test('finds vendor prefixed values', () => {
 		uniquenessRatio: 1,
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
 test('finds non-shorthands, logical properties', () => {
@@ -166,7 +164,7 @@ test('finds non-shorthands, logical properties', () => {
 		uniquenessRatio: 1 / 4,
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
 test('finds non-shorthands, non-logical properties', () => {
@@ -222,7 +220,7 @@ test('finds non-shorthands, non-logical properties', () => {
 		uniquenessRatio: 1 / 4,
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
 test('ignores keywords', () => {
@@ -247,7 +245,6 @@ test('ignores keywords', () => {
 		uniquenessRatio: 0
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
-test.run()
diff --git a/src/values/box-shadows.test.js b/src/values/box-shadows.test.ts
similarity index 77%
rename from src/values/box-shadows.test.js
rename to src/values/box-shadows.test.ts
index 401a97b1..e5603863 100644
--- a/src/values/box-shadows.test.js
+++ b/src/values/box-shadows.test.ts
@@ -1,10 +1,8 @@
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
+import { test } from 'vitest'
+import { expect } from 'vitest'
 import { analyze } from '../index.js'
 
-const BoxShadows = suite('BoxShadows')
-
-BoxShadows('finds simple values', () => {
+test('finds simple values', () => {
   const fixture = `
     box-shadows-simple {
       box-shadow: 1px 1px 2px black;
@@ -20,10 +18,10 @@ BoxShadows('finds simple values', () => {
     uniquenessRatio: 1
   }
 
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-BoxShadows('finds complex values', () => {
+test('finds complex values', () => {
   const fixture = `
     box-shadows-complex {
       box-shadow: 1px 1px 1px black,inset 2px 3px 5px rgba(0,0,0,0.3),inset -2px -3px 5px rgba(255,255,255,0.5);
@@ -39,10 +37,10 @@ BoxShadows('finds complex values', () => {
     uniquenessRatio: 1
   }
 
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-BoxShadows('finds vendor prefixed values', () => {
+test('finds vendor prefixed values', () => {
   const fixture = `
     box-shadows-vendor-prefixed {
       -webkit-box-shadow: 1px 1px 2px black;
@@ -58,10 +56,10 @@ BoxShadows('finds vendor prefixed values', () => {
     uniquenessRatio: 1
   }
 
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-BoxShadows.skip('does not report var() fallback values as separate values', () => {
+test.skip('does not report var() fallback values as separate values', () => {
   const fixture = `
     with-fallback {
       box-shadow: var(--tw-ring-offset-shadow, 0 0 #0000), var(--tw-ring-shadow, 0 0 #0000), var(--tw-shadow);
@@ -75,10 +73,10 @@ BoxShadows.skip('does not report var() fallback values as separate values', () =
     totalUnique: 1,
     uniquenessRatio: 1
   }
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-BoxShadows('ignores keywords', () => {
+test('ignores keywords', () => {
   const fixture = `
     box-shadows-keyword {
       box-shadow: none;
@@ -99,7 +97,6 @@ BoxShadows('ignores keywords', () => {
     uniquenessRatio: 0
   }
 
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-BoxShadows.run()
\ No newline at end of file
diff --git a/src/values/browserhacks.js b/src/values/browserhacks.js
deleted file mode 100644
index 8e0d1d97..00000000
--- a/src/values/browserhacks.js
+++ /dev/null
@@ -1,16 +0,0 @@
-import { endsWith } from "../string-utils.js"
-import { Identifier } from "../css-tree-node-types.js"
-
-/**
- * @param {import('css-tree').Value} node
- */
-export function isIe9Hack(node) {
-	let children = node.children
-	if (children) {
-		let last = children.last
-		return last
-			&& last.type === Identifier
-			&& endsWith('\\9', last.name)
-	}
-	return false
-}
diff --git a/src/values/browserhacks.test.js b/src/values/browserhacks.test.ts
similarity index 72%
rename from src/values/browserhacks.test.js
rename to src/values/browserhacks.test.ts
index 2e18e3f5..68432ce0 100644
--- a/src/values/browserhacks.test.js
+++ b/src/values/browserhacks.test.ts
@@ -1,10 +1,8 @@
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
+import { test } from 'vitest'
+import { expect } from 'vitest'
 import { analyze } from '../index.js'
 
-const Browserhacks = suite('Values - Browserhacks')
-
-Browserhacks('finds hacks', () => {
+test('finds hacks', () => {
   const fixture = `
     value-browserhacks {
       property: value !ie;
@@ -25,10 +23,10 @@ Browserhacks('finds hacks', () => {
     },
     uniquenessRatio: 4 / 4
   }
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-Browserhacks('reports no false positives', () => {
+test('reports no false positives', () => {
   const fixture = `
     value-browserhacks {
       property: value !important;
@@ -43,7 +41,6 @@ Browserhacks('reports no false positives', () => {
     unique: {},
     uniquenessRatio: 0,
   }
-  assert.equal(actual, expected)
+  expect(actual).toEqual(expected)
 })
 
-Browserhacks.run()
\ No newline at end of file
diff --git a/src/values/browserhacks.ts b/src/values/browserhacks.ts
new file mode 100644
index 00000000..83f6f3f3
--- /dev/null
+++ b/src/values/browserhacks.ts
@@ -0,0 +1,12 @@
+import { endsWith } from '../string-utils.js'
+import { Identifier } from '../css-tree-node-types.js'
+import type { Value } from 'css-tree'
+
+export function isIe9Hack(node: Value): boolean {
+	let children = node.children
+	if (children) {
+		let last = children.last
+		return last && last.type === Identifier && endsWith('\\9', last.name) ? true : false
+	}
+	return false
+}
diff --git a/src/values/colors.js b/src/values/colors.js
deleted file mode 100644
index d2052d46..00000000
--- a/src/values/colors.js
+++ /dev/null
@@ -1,199 +0,0 @@
-import { KeywordSet } from "../keyword-set.js"
-
-export const namedColors = new KeywordSet([
-  // CSS Named Colors
-  // Spec: https://drafts.csswg.org/css-color/#named-colors
-
-  // Heuristic: popular names first for quick finding in set.has()
-  // See: https://docs.google.com/spreadsheets/d/1OU8ahxC5oYU8VRryQs9BzHToaXcOntVlh6KUHjm15G4/edit#gid=2096495459
-  'white',
-  'black',
-  'red',
-  'gray',
-  'silver',
-  'grey',
-  'green',
-  'orange',
-  'blue',
-  'dimgray',
-  'whitesmoke',
-  'lightgray',
-  'lightgrey',
-  'yellow',
-  'gold',
-  'pink',
-  'gainsboro',
-  'magenta',
-  'purple',
-  'darkgray',
-  'navy',
-  'darkred',
-  'teal',
-  'maroon',
-  'darkgrey',
-  'tomato',
-  'darkorange',
-  'brown',
-  'crimson',
-  'lightyellow',
-  'slategray',
-  'salmon',
-  'lightgreen',
-  'lightblue',
-  'orangered',
-  'aliceblue',
-  'dodgerblue',
-  'lime',
-  'darkblue',
-  'darkgoldenrod',
-  'skyblue',
-  'royalblue',
-  'darkgreen',
-  'ivory',
-  'olive',
-  'aqua',
-  'turquoise',
-  'cyan',
-  'khaki',
-  'beige',
-  'snow',
-  'ghostwhite',
-  'limegreen',
-  'coral',
-  'dimgrey',
-  'hotpink',
-  'midnightblue',
-  'firebrick',
-  'indigo',
-  'wheat',
-  'mediumblue',
-  'lightpink',
-  'plum',
-  'azure',
-  'violet',
-  'lavender',
-  'deepskyblue',
-  'darkslategrey',
-  'goldenrod',
-  'cornflowerblue',
-  'lightskyblue',
-  'indianred',
-  'yellowgreen',
-  'saddlebrown',
-  'palegreen',
-  'bisque',
-  'tan',
-  'antiquewhite',
-  'steelblue',
-  'forestgreen',
-  'fuchsia',
-  'mediumaquamarine',
-  'seagreen',
-  'sienna',
-  'deeppink',
-  'mediumseagreen',
-  'peru',
-  'greenyellow',
-  'lightgoldenrodyellow',
-  'orchid',
-  'cadetblue',
-  'navajowhite',
-  'lightsteelblue',
-  'slategrey',
-  'linen',
-  'lightseagreen',
-  'darkcyan',
-  'lightcoral',
-  'aquamarine',
-  'blueviolet',
-  'cornsilk',
-  'lightsalmon',
-  'chocolate',
-  'lightslategray',
-  'floralwhite',
-  'darkturquoise',
-  'darkslategray',
-  'rebeccapurple',
-  'burlywood',
-  'chartreuse',
-  'lightcyan',
-  'lemonchiffon',
-  'palevioletred',
-  'darkslateblue',
-  'mediumpurple',
-  'lawngreen',
-  'slateblue',
-  'darkseagreen',
-  'blanchedalmond',
-  'mistyrose',
-  'darkolivegreen',
-  'seashell',
-  'olivedrab',
-  'peachpuff',
-  'darkviolet',
-  'powderblue',
-  'darkmagenta',
-  'lightslategrey',
-  'honeydew',
-  'palegoldenrod',
-  'darkkhaki',
-  'oldlace',
-  'mintcream',
-  'sandybrown',
-  'mediumturquoise',
-  'papayawhip',
-  'paleturquoise',
-  'mediumvioletred',
-  'thistle',
-  'springgreen',
-  'moccasin',
-  'rosybrown',
-  'lavenderblush',
-  'mediumslateblue',
-  'darkorchid',
-  'mediumorchid',
-  'darksalmon',
-  'mediumspringgreen',
-])
-
-export const systemColors = new KeywordSet([
-  // CSS System Colors
-  // Spec: https://drafts.csswg.org/css-color/#css-system-colors
-  'accentcolor',
-  'accentcolortext',
-  'activetext',
-  'buttonborder',
-  'buttonface',
-  'buttontext',
-  'canvas',
-  'canvastext',
-  'field',
-  'fieldtext',
-  'graytext',
-  'highlight',
-  'highlighttext',
-  'linktext',
-  'mark',
-  'marktext',
-  'selecteditem',
-  'selecteditemtext',
-  'visitedtext',
-])
-
-export const colorFunctions = new KeywordSet([
-  'rgba',
-  'rgb',
-  'hsla',
-  'hsl',
-  'oklch',
-  'color',
-  'hwb',
-  'lch',
-  'lab',
-  'oklab',
-])
-
-export const colorKeywords = new KeywordSet([
-  'transparent',
-  'currentcolor',
-])
diff --git a/src/values/colors.test.js b/src/values/colors.test.js
deleted file mode 100644
index 5ddd64fc..00000000
--- a/src/values/colors.test.js
+++ /dev/null
@@ -1,1102 +0,0 @@
-import { suite } from 'uvu';
-import * as assert from 'uvu/assert';
-import { analyze } from '../index.js'
-
-const Colors = suite('Colors')
-
-Colors('finds hex colors', () => {
-  const actual = analyze(`
-    test {
-      color: #000;
-      color: #1111;
-      color: #222222;
-      color: #33333333;
-    }
-
-    test-bg {
-      background: linear-gradient(90deg, #444 0, #444 100%);
-    }
-
-    test-box-shadow {
-      box-shadow: 0 0 0 #555;
-    }
-
-    test-outline-color {
-      outline-color: #666;
-    }
-
-    test-custom-property {
-      test: #777;
-    }
-
-    test-hex-casing {
-      casing: #AaBbCc;
-    }
-
-    #not-a-color {
-      margin: 0;
-    }
-  `).values.colors;
-
-  const expected = {
-    total: 10,
-    totalUnique: 9,
-    unique: {
-      '#000': 1,
-      '#1111': 1,
-      '#222222': 1,
-      '#33333333': 1,
-      '#444': 2,
-      '#555': 1,
-      '#666': 1,
-      '#777': 1,
-      '#AaBbCc': 1,
-    },
-    uniquenessRatio: 9 / 10,
-    itemsPerContext: {
-      color: {
-        total: 4,
-        totalUnique: 4,
-        uniquenessRatio: 1,
-        unique: {
-          '#000': 1,
-          '#1111': 1,
-          '#222222': 1,
-          '#33333333': 1,
-        },
-      },
-      background: {
-        total: 2,
-        totalUnique: 1,
-        uniquenessRatio: 1 / 2,
-        unique: {
-          '#444': 2,
-        },
-      },
-      'box-shadow': {
-        total: 1,
-        totalUnique: 1,
-        uniquenessRatio: 1,
-        unique: {
-          '#555': 1,
-        },
-      },
-      'outline-color': {
-        total: 1,
-        totalUnique: 1,
-        uniquenessRatio: 1,
-        unique: {
-          '#666': 1,
-        }
-      },
-      'test': {
-        total: 1,
-        totalUnique: 1,
-        uniquenessRatio: 1,
-        unique: {
-          '#777': 1,
-        },
-      },
-      'casing': {
-        total: 1,
-        totalUnique: 1,
-        uniquenessRatio: 1,
-        unique: {
-          '#AaBbCc': 1,
-        },
-      },
-    },
-    formats: {
-      "total": 10,
-      "totalUnique": 4,
-      "unique": {
-        hex3: 6,
-        hex4: 1,
-        hex6: 2,
-        hex8: 1,
-      },
-      "uniquenessRatio": 4 / 10,
-    }
-  }
-  assert.equal(actual, expected)
-})
-
-Colors('Counts hex format correctly when combined with a browserhack', () => {
-  let actual = analyze(`
-    a {
-      color: #000\\9;
-    }
-  `)
-  let expected = {
-    total: 1,
-    totalUnique: 1,
-    unique: {
-      '#000\\9': 1,
-    },
-    uniquenessRatio: 1,
-    itemsPerContext: {
-      color: {
-        total: 1,
-        totalUnique: 1,
-        uniquenessRatio: 1,
-        unique: {
-          '#000\\9': 1,
-        },
-      },
-    },
-    formats: {
-      total: 1,
-      totalUnique: 1,
-      unique: {
-        hex3: 1,
-      },
-      uniquenessRatio: 1,
-    }
-  }
-  assert.equal(actual.values.colors, expected);
-})
-
-Colors('finds hsl(a) colors', () => {
-  const actual = analyze(`
-    test {
-      color: hsl(1, 20%, 30%);
-      color: hsl(1 20% 30% / 1);
-      color: Hsla(2, 20%, 30%, 0.5);
-    }
-
-    test-bg {
-      background: linear-gradient(90deg, hsl(3, 20%, 30%) 0, hsl(3, 20%, 30%) 100%);
-    }
-
-    test-box-shadow {
-      box-shadow: 0 0 0 hsl(4, 20%, 30%);
-    }
-
-    test-outline-color {
-      outline-color: hsl(5, 20%, 30%);
-    }
-
-    test-custom-property {
-      test: hsl(6, 20%, 30%);
-    }
-
-    test-notations {
-      color: hsl(30, 100%, 50%, 0.6);
-      color: hsla(30, 100%, 50%, 0.6);
-      color: hsl(30 100% 50% / 0.6);
-      color: hsla(30 100% 50% / 0.6);
-      color: hsl(30.0 100% 50% / 60%);
-      color: hsla(30.2 100% 50% / 60%);
-
-      /* Source: https://developer.mozilla.org/en-US/docs/Web/CSS/color_value#hsl_syntax_variations */
-      /* These examples all specify the same color: a lavender. */
-      color: hsl(270,60%,70%);
-      color: hsl(270, 60%, 70%);
-      color: hsl(270 60% 70%);
-      color: hsl(270deg, 60%, 70%);
-      color: hsl(4.71239rad, 60%, 70%);
-      color: hsl(.75turn, 60%, 70%);
-
-      /* These examples all specify the same color: a lavender that is 15% opaque. */
-      color: hsl(270, 60%, 50%, .15);
-      color: hsl(270, 60%, 50%, 15%);
-      color: hsl(270 60% 50% / .15);
-      color: hsl(270 60% 50% / 15%);
-    }
-  `).values.colors;
-
-  const expected = {
-    total: 24,
-    totalUnique: 23,
-    unique: {
-      'hsl(1, 20%, 30%)': 1,
-      'hsl(1 20% 30% / 1)': 1,
-      'Hsla(2, 20%, 30%, 0.5)': 1,
-      'hsl(3, 20%, 30%)': 2,
-      'hsl(4, 20%, 30%)': 1,
-      'hsl(5, 20%, 30%)': 1,
-      'hsl(6, 20%, 30%)': 1,
-      'hsl(30, 100%, 50%, 0.6)': 1,
-      'hsla(30, 100%, 50%, 0.6)': 1,
-      'hsl(30 100% 50% / 0.6)': 1,
-      'hsla(30 100% 50% / 0.6)': 1,
-      'hsl(30.0 100% 50% / 60%)': 1,
-      'hsla(30.2 100% 50% / 60%)': 1,
-      'hsl(270,60%,70%)': 1,
-      'hsl(270, 60%, 70%)': 1,
-      'hsl(270 60% 70%)': 1,
-      'hsl(270deg, 60%, 70%)': 1,
-      'hsl(4.71239rad, 60%, 70%)': 1,
-      'hsl(.75turn, 60%, 70%)': 1,
-      'hsl(270, 60%, 50%, .15)': 1,
-      'hsl(270, 60%, 50%, 15%)': 1,
-      'hsl(270 60% 50% / .15)': 1,
-      'hsl(270 60% 50% / 15%)': 1,
-    },
-    uniquenessRatio: 23 / 24,
-    itemsPerContext: {
-      color: {
-        total: 19,
-        totalUnique: 19,
-        unique: {
-          'hsl(1, 20%, 30%)': 1,
-          'hsl(1 20% 30% / 1)': 1,
-          'Hsla(2, 20%, 30%, 0.5)': 1,
-          'hsl(30, 100%, 50%, 0.6)': 1,
-          'hsla(30, 100%, 50%, 0.6)': 1,
-          'hsl(30 100% 50% / 0.6)': 1,
-          'hsla(30 100% 50% / 0.6)': 1,
-          'hsl(30.0 100% 50% / 60%)': 1,
-          'hsla(30.2 100% 50% / 60%)': 1,
-          'hsl(270,60%,70%)': 1,
-          'hsl(270, 60%, 70%)': 1,
-          'hsl(270 60% 70%)': 1,
-          'hsl(270deg, 60%, 70%)': 1,
-          'hsl(4.71239rad, 60%, 70%)': 1,
-          'hsl(.75turn, 60%, 70%)': 1,
-          'hsl(270, 60%, 50%, .15)': 1,
-          'hsl(270, 60%, 50%, 15%)': 1,
-          'hsl(270 60% 50% / .15)': 1,
-          'hsl(270 60% 50% / 15%)': 1,
-        },
-        uniquenessRatio: 1,
-      },
-      background: {
-        total: 2,
-        totalUnique: 1,
-        unique: {
-          'hsl(3, 20%, 30%)': 2
-        },
-        uniquenessRatio: 0.5
-      },
-      'box-shadow': {
-        total: 1,
-        totalUnique: 1,
-        unique: {
-          'hsl(4, 20%, 30%)': 1
-        },
-        uniquenessRatio: 1
-      },
-      'outline-color': {
-        total: 1,
-        totalUnique: 1,
-        unique: {
-          'hsl(5, 20%, 30%)': 1
-        },
-        uniquenessRatio: 1
-      },
-      'test': {
-        total: 1,
-        totalUnique: 1,
-        unique: {
-          'hsl(6, 20%, 30%)': 1
-        },
-        uniquenessRatio: 1
-      }
-    },
-    formats: {
-      total: 24,
-      totalUnique: 2,
-      unique: {
-        hsl: 20,
-        hsla: 4,
-      },
-      uniquenessRatio: 2 / 24,
-    },
-  }
-  assert.equal(actual, expected)
-})
-
-Colors('finds rgb(a) colors', () => {
-  const actual = analyze(`
-    test {
-      color: rgb(1, 1, 1);
-      color: rgba(2, 2, 2, 0.2);
-      color: RGBA(3, 3, 3, .3);
-      color: rgba(4,4,4,.4)
-    }
-
-    test-bg {
-      background: linear-gradient(90deg, rgb(5, 5, 5) 0, rgb(5, 5, 5) 100%);
-    }
-
-    test-box-shadow {
-      box-shadow: 0 0 0 rgb(6,6,6);
-    }
-
-    test-outline-color {
-      outline-color: rgb(7,7,7);
-    }
-
-    test-custom-property {
-      test: rgb(8,8,8);
-    }
-
-    /* Source: https://developer.mozilla.org/en-US/docs/Web/CSS/color */
-    test-notations {
-      color: rgb(34, 12, 64, 0.6);
-      color: rgba(34, 12, 64, 0.6);
-      color: rgb(34 12 64 / 0.6);
-      color: rgba(34 12 64 / 0.3);
-      color: rgb(34.0 12 64 / 60%);
-      color: rgba(34.6 12 64 / 30%);
-      color: rgba(255, 0, 153.6, 1);
-    }
-
-    /* https://developer.mozilla.org/en-US/docs/Web/CSS/color_value#rgb_transparency_variations */
-    test-exotic-numbers {
-      color: rgba(1e2, .5e1, .5e0, +.25e2%);
-    }
-  `).values.colors;
-
-  const expected = {
-    total: 17,
-    totalUnique: 16,
-    unique: {
-      'rgb(1, 1, 1)': 1,
-      'rgba(2, 2, 2, 0.2)': 1,
-      'RGBA(3, 3, 3, .3)': 1,
-      'rgba(4,4,4,.4)': 1,
-      'rgb(5, 5, 5)': 2,
-      'rgb(6,6,6)': 1,
-      'rgb(7,7,7)': 1,
-      'rgb(8,8,8)': 1,
-      'rgb(34, 12, 64, 0.6)': 1,
-      'rgba(34, 12, 64, 0.6)': 1,
-      'rgb(34 12 64 / 0.6)': 1,
-      'rgba(34 12 64 / 0.3)': 1,
-      'rgb(34.0 12 64 / 60%)': 1,
-      'rgba(34.6 12 64 / 30%)': 1,
-      'rgba(255, 0, 153.6, 1)': 1,
-      'rgba(1e2, .5e1, .5e0, +.25e2%)': 1,
-    },
-    uniquenessRatio: 16 / 17,
-    itemsPerContext: {
-      color: {
-        total: 12,
-        totalUnique: 12,
-        unique: {
-          'rgb(1, 1, 1)': 1,
-          'rgba(2, 2, 2, 0.2)': 1,
-          'RGBA(3, 3, 3, .3)': 1,
-          'rgba(4,4,4,.4)': 1,
-          'rgb(34, 12, 64, 0.6)': 1,
-          'rgba(34, 12, 64, 0.6)': 1,
-          'rgb(34 12 64 / 0.6)': 1,
-          'rgba(34 12 64 / 0.3)': 1,
-          'rgb(34.0 12 64 / 60%)': 1,
-          'rgba(34.6 12 64 / 30%)': 1,
-          'rgba(255, 0, 153.6, 1)': 1,
-          'rgba(1e2, .5e1, .5e0, +.25e2%)': 1
-        },
-        uniquenessRatio: 1,
-      },
-      background: {
-        total: 2,
-        totalUnique: 1,
-        unique: {
-          'rgb(5, 5, 5)': 2
-        },
-        uniquenessRatio: 0.5,
-      },
-      'box-shadow': {
-        total: 1,
-        totalUnique: 1,
-        unique: {
-          'rgb(6,6,6)': 1
-        },
-        uniquenessRatio: 1,
-      },
-      'outline-color': {
-        total: 1,
-        totalUnique: 1,
-        unique: {
-          'rgb(7,7,7)': 1
-        },
-        uniquenessRatio: 1,
-      },
-      'test': {
-        total: 1,
-        totalUnique: 1,
-        unique: {
-          'rgb(8,8,8)': 1
-        },
-        uniquenessRatio: 1,
-      },
-    },
-    formats: {
-      total: 17,
-      totalUnique: 2,
-      unique: {
-        rgb: 9,
-        rgba: 8
-      },
-      uniquenessRatio: 2 / 17,
-    },
-  }
-  assert.equal(actual, expected)
-})
-
-Colors('finds LCH() colors', () => {
-  const actual = analyze(`
-    .lch {
-      /* Source: https://developer.mozilla.org/en-US/docs/Web/CSS/color_value/lch() */
-      color: lch(29.2345% 44.2 27);
-      color: lch(52.2345% 72.2 56.2);
-
-      /* Capitalisation */
-      color: LCH(29.2345% 44.2 27);
-      color: Lch(29.2345% 44.2 27);
-
-      /* Opacity notations */
-      color: lch(52.2345% 72.2 56.2 / 1);
-      color: lch(52.2345% 72.2 56.2 / .5);
-      color: lch(52.2345% 72.2 56.2 / 0.5);
-      color: lch(52.2345% 72.2 56.2 / 50%);
-    }
-  `)
-  const expected = {
-    total: 8,
-    totalUnique: 8,
-    unique: {
-      'lch(29.2345% 44.2 27)': 1,
-      'lch(52.2345% 72.2 56.2)': 1,
-
-      /* Capitalisation */
-      'LCH(29.2345% 44.2 27)': 1,
-      'Lch(29.2345% 44.2 27)': 1,
-
-      /* Opacity notations */
-      'lch(52.2345% 72.2 56.2 / 1)': 1,
-      'lch(52.2345% 72.2 56.2 / .5)': 1,
-      'lch(52.2345% 72.2 56.2 / 0.5)': 1,
-      'lch(52.2345% 72.2 56.2 / 50%)': 1,
-    },
-    uniquenessRatio: 1,
-    itemsPerContext: {
-      color: {
-        total: 8,
-        totalUnique: 8,
-        unique: {
-          'lch(29.2345% 44.2 27)': 1,
-          'lch(52.2345% 72.2 56.2)': 1,
-          'LCH(29.2345% 44.2 27)': 1,
-          'Lch(29.2345% 44.2 27)': 1,
-          'lch(52.2345% 72.2 56.2 / 1)': 1,
-          'lch(52.2345% 72.2 56.2 / .5)': 1,
-          'lch(52.2345% 72.2 56.2 / 0.5)': 1,
-          'lch(52.2345% 72.2 56.2 / 50%)': 1
-        },
-        uniquenessRatio: 1,
-      },
-    },
-    formats: {
-      total: 8,
-      totalUnique: 1,
-      unique: {
-        lch: 8,
-      },
-      uniquenessRatio: 1 / 8,
-    },
-  }
-
-  assert.equal(actual.values.colors, expected)
-})
-
-Colors('finds LAB() colors', () => {
-  const actual = analyze(`
-    .lch {
-      /* Source: https://drafts.csswg.org/css-color/#specifying-lab-lch */
-      color: lab(52.2345% 40.1645 59.9971);
-      color: lab(60.2345% -5.3654 58.956);
-      color: lab(62.2345% -34.9638 47.7721);
-      color: lab(67.5345% -8.6911 -41.6019);
-
-      /* Capitalisation */
-      color: lab(29.2345% 39.3825 20.0664);
-      color: Lab(29.2345% 39.3825 20.0664);
-      color: LAB(29.2345% 39.3825 20.0664);
-
-      /* Opacity notations */
-      color: lab(52.2345% 40.1645 59.9971 / 0);
-      color: lab(52.2345% 40.1645 59.9971 / .5);
-      color: lab(52.2345% 40.1645 59.9971 / 0.5);
-      color: lab(52.2345% 40.1645 59.9971 / 50%);
-    }
-  `)
-  const expected = {
-    total: 11,
-    totalUnique: 11,
-    unique: {
-      'lab(52.2345% 40.1645 59.9971)': 1,
-      'lab(60.2345% -5.3654 58.956)': 1,
-      'lab(62.2345% -34.9638 47.7721)': 1,
-      'lab(67.5345% -8.6911 -41.6019)': 1,
-
-      /* Capitalisation */
-      'lab(29.2345% 39.3825 20.0664)': 1,
-      'Lab(29.2345% 39.3825 20.0664)': 1,
-      'LAB(29.2345% 39.3825 20.0664)': 1,
-
-      /* Opacity notations */
-      'lab(52.2345% 40.1645 59.9971 / 0)': 1,
-      'lab(52.2345% 40.1645 59.9971 / .5)': 1,
-      'lab(52.2345% 40.1645 59.9971 / 0.5)': 1,
-      'lab(52.2345% 40.1645 59.9971 / 50%)': 1,
-    },
-    uniquenessRatio: 1,
-    'itemsPerContext': {
-      'color': {
-        'total': 11,
-        'totalUnique': 11,
-        'unique': {
-          'lab(52.2345% 40.1645 59.9971)': 1,
-          'lab(60.2345% -5.3654 58.956)': 1,
-          'lab(62.2345% -34.9638 47.7721)': 1,
-          'lab(67.5345% -8.6911 -41.6019)': 1,
-          'lab(29.2345% 39.3825 20.0664)': 1,
-          'Lab(29.2345% 39.3825 20.0664)': 1,
-          'LAB(29.2345% 39.3825 20.0664)': 1,
-          'lab(52.2345% 40.1645 59.9971 / 0)': 1,
-          'lab(52.2345% 40.1645 59.9971 / .5)': 1,
-          'lab(52.2345% 40.1645 59.9971 / 0.5)': 1,
-          'lab(52.2345% 40.1645 59.9971 / 50%)': 1
-        },
-        uniquenessRatio: 1,
-      },
-    },
-    formats: {
-      total: 11,
-      totalUnique: 1,
-      unique: {
-        lab: 11
-      },
-      uniquenessRatio: 1 / 11,
-    },
-  }
-
-  assert.equal(actual.values.colors, expected)
-})
-
-Colors('finds hwb() colors', () => {
-  const actual = analyze(`
-    .hwb {
-      color: hwb(194 0% 0%);
-      color: hwb(194, 0%, 0%);
-
-      color: Hwb(194 0% 0%);
-      color: HWB(194 0% 0%);
-
-      color: hwb(194 0% 0% / .5);
-      color: hwb(194 0% 0% / 0.5);
-      color: hwb(194 0% 0% / 50%);
-    }
-  `)
-  const expected = {
-    total: 7,
-    totalUnique: 7,
-    uniquenessRatio: 1,
-    unique: {
-      'hwb(194 0% 0%)': 1,
-      'hwb(194, 0%, 0%)': 1,
-
-      'Hwb(194 0% 0%)': 1,
-      'HWB(194 0% 0%)': 1,
-
-      'hwb(194 0% 0% / .5)': 1,
-      'hwb(194 0% 0% / 0.5)': 1,
-      'hwb(194 0% 0% / 50%)': 1,
-    },
-    itemsPerContext: {
-      color: {
-        total: 7,
-        totalUnique: 7,
-        unique: {
-          'hwb(194 0% 0%)': 1,
-          'hwb(194, 0%, 0%)': 1,
-          'Hwb(194 0% 0%)': 1,
-          'HWB(194 0% 0%)': 1,
-          'hwb(194 0% 0% / .5)': 1,
-          'hwb(194 0% 0% / 0.5)': 1,
-          'hwb(194 0% 0% / 50%)': 1
-        },
-        uniquenessRatio: 1,
-      }
-    },
-    formats: {
-      total: 7,
-      totalUnique: 1,
-      unique: {
-        hwb: 7,
-      },
-      uniquenessRatio: 1 / 7,
-    },
-  }
-
-  assert.equal(actual.values.colors, expected)
-})
-
-Colors('finds color() colors', () => {
-  const actual = analyze(`
-    .colors {
-      color: color(rec2020 0.42053 0.979780 0.00579);
-      color: color(display-p3 -0.6112 1.0079 -0.2192);
-      color: color(profoto-rgb 0.4835 0.9167 0.2188);
-      color: color(xyz-d50 0.2005 0.14089 0.4472);
-    }
-  `)
-  const expected = {
-    total: 4,
-    totalUnique: 4,
-    unique: {
-      'color(rec2020 0.42053 0.979780 0.00579)': 1,
-      'color(display-p3 -0.6112 1.0079 -0.2192)': 1,
-      'color(profoto-rgb 0.4835 0.9167 0.2188)': 1,
-      'color(xyz-d50 0.2005 0.14089 0.4472)': 1,
-    },
-    uniquenessRatio: 1,
-    itemsPerContext: {
-      color: {
-        total: 4,
-        totalUnique: 4,
-        unique: {
-          'color(rec2020 0.42053 0.979780 0.00579)': 1,
-          'color(display-p3 -0.6112 1.0079 -0.2192)': 1,
-          'color(profoto-rgb 0.4835 0.9167 0.2188)': 1,
-          'color(xyz-d50 0.2005 0.14089 0.4472)': 1
-        },
-        uniquenessRatio: 1
-      },
-    },
-    formats: {
-      total: 4,
-      totalUnique: 1,
-      unique: {
-        color: 4,
-      },
-      uniquenessRatio: 1 / 4,
-    },
-  }
-
-  assert.equal(actual.values.colors, expected)
-})
-
-Colors('finds color keywords', () => {
-  const actual = analyze(`
-    test {
-      outline: 1px solid tomato;
-      border-color: Aqua;
-      outline-color: whitesmoke;
-      background: linear-gradient(90deg, purple 0, purple 100%);
-    }
-  `).values.colors
-  const expected = {
-    total: 5,
-    totalUnique: 4,
-    unique: {
-      'tomato': 1,
-      'Aqua': 1,
-      'whitesmoke': 1,
-      'purple': 2,
-    },
-    uniquenessRatio: 4 / 5,
-    itemsPerContext: {
-      outline: {
-        total: 1,
-        totalUnique: 1,
-        unique: {
-          tomato: 1,
-        },
-        uniquenessRatio: 1,
-      },
-      'border-color': {
-        total: 1,
-        totalUnique: 1,
-        unique: {
-          Aqua: 1,
-        },
-        uniquenessRatio: 1,
-      },
-      'outline-color': {
-        total: 1,
-        totalUnique: 1,
-        unique: {
-          whitesmoke: 1
-        },
-        uniquenessRatio: 1,
-      },
-      background: {
-        total: 2,
-        totalUnique: 1,
-        unique: {
-          purple: 2
-        },
-        uniquenessRatio: 0.5,
-      },
-    },
-    formats: {
-      total: 5,
-      totalUnique: 1,
-      unique: {
-        named: 5,
-      },
-      uniquenessRatio: 1 / 5,
-    },
-  }
-  assert.equal(actual, expected)
-})
-
-Colors('does not report false positives for color keywords', () => {
-  const actual = analyze(`
-    test {
-      /* Not a blue keyword */
-      background: url(icon-blue.png), url(blue-icon.png), url(blue_icon.png), url(icon_blue.png);
-
-      /* Not a hex color */
-      background-image: url(#footer-logo-text-linear-gradient);
-
-      /* Not the white color keyword */
-      white-space: nowrap;
-
-      /* Not the linen color keyword */
-      counter-increment: lineNo;
-
-      /* Not the gray keyword */
-      -moz-osx-font-smoothing: grayscale;
-
-      /* Not the black color keyword */
-      font-family: Arial Black, Arial Bold, Gadget, sans-serif;
-      font: 1em/1 Black;
-
-      /* not a color keyword */
-      -ms-overflow-style: scrollbar;
-    }
-  `).values.colors
-  const expected = {
-    total: 0,
-    totalUnique: 0,
-    unique: {},
-    uniquenessRatio: 0,
-    itemsPerContext: {},
-    formats: {
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-    },
-  }
-
-  assert.equal(actual, expected)
-})
-
-// Source: https://gist.github.com/lahmatiy/84c7fd877a78e561cac57e59e142c9e3
-Colors.skip('ignores color names that are not actual colors', () => {
-  const fixture = `
-    test {
-      animation: red; /* it's not a color but an animation name */
-      unknown-property: blue; /* don't match value as a color when property is unknown */
-    }
-  `
-  const actual = analyze(fixture).values.colors
-  const expected = {
-    total: 0,
-    totalUnique: 0,
-    unique: {},
-    uniquenessRatio: 0,
-    itemsPerContext: {},
-    formats: {
-      total: 0,
-      totalUnique: 0,
-      unique: {},
-      uniquenessRatio: 0,
-    },
-  }
-
-  assert.equal(actual, expected)
-})
-
-Colors('finds colors in var() as fallback values', () => {
-  const fixture = `
-    test {
-      --main: #aaa;
-      color: var(--main, #eee);
-
-      /* from github */
-      box-shadow: 0 3px 12px var(--color-fade-black-15), 0 0 1px rgba(27, 31, 35, .2);
-      text-shadow: 0 0 var(--main, var(--sec, #000));
-    }
-  `
-  const result = analyze(fixture)
-  const actual = result.values.colors
-  const expected = {
-    total: 4,
-    totalUnique: 4,
-    unique: {
-      '#aaa': 1,
-      '#eee': 1,
-      'rgba(27, 31, 35, .2)': 1,
-      '#000': 1,
-    },
-    uniquenessRatio: 4 / 4,
-    itemsPerContext: {
-      '--main': {
-        total: 1,
-        totalUnique: 1,
-        unique: {
-          '#aaa': 1,
-        },
-        uniquenessRatio: 1,
-      },
-      'color': {
-        total: 1,
-        totalUnique: 1,
-        unique: {
-          '#eee': 1,
-        },
-        uniquenessRatio: 1,
-      },
-      'box-shadow': {
-        total: 1,
-        totalUnique: 1,
-        unique: {
-          'rgba(27, 31, 35, .2)': 1,
-        },
-        uniquenessRatio: 1,
-      },
-      'text-shadow': {
-        total: 1,
-        totalUnique: 1,
-        unique: {
-          '#000': 1,
-        },
-        uniquenessRatio: 1,
-      },
-    },
-    formats: {
-      total: 4,
-      totalUnique: 2,
-      unique: {
-        hex3: 3,
-        rgba: 1,
-      },
-      uniquenessRatio: 2 / 4,
-    }
-  }
-
-  assert.equal(actual, expected)
-})
-
-Colors('ignores CSS keywords', () => {
-  const fixture = `
-    testColorKeywords {
-      color: currentColor;
-      color: currentcolor;
-      color: inherit;
-      color: unset;
-      color: initial;
-      color: transparent;
-      color: revert;
-      color: revert-layer;
-      background: none;
-    }
-
-    positive {
-      background: none 0px 0px repeat scroll rgb(0, 0, 0);
-    }
-  `
-  const actual = analyze(fixture).values.colors
-  const expected = {
-    total: 4,
-    totalUnique: 4,
-    unique: {
-      'currentColor': 1,
-      'currentcolor': 1,
-      transparent: 1,
-      'rgb(0, 0, 0)': 1,
-    },
-    uniquenessRatio: 4 / 4,
-    itemsPerContext: {
-      color: {
-        total: 3,
-        totalUnique: 3,
-        unique: {
-          'currentColor': 1,
-          'currentcolor': 1,
-          transparent: 1,
-        },
-        uniquenessRatio: 3 / 3,
-      },
-      background: {
-        total: 1,
-        totalUnique: 1,
-        unique: {
-          'rgb(0, 0, 0)': 1,
-        },
-        uniquenessRatio: 1,
-      },
-    },
-    formats: {
-      "total": 4,
-      "totalUnique": 3,
-      "unique": {
-        currentcolor: 2,
-        transparent: 1,
-        rgb: 1,
-      },
-      "uniquenessRatio": 3 / 4,
-    }
-  }
-
-  assert.equal(actual, expected)
-})
-
-// https://drafts.csswg.org/css-color/#css-system-colors
-Colors('finds System Colors', () => {
-  const fixture = `
-    color: test-system-colors {
-      color: Canvas;
-      color: CanvasText;
-      color: Linktext;
-      color: VisitedText;
-      color: ActiveText;
-      color: ButtonFace;
-      color: ButtonText;
-      color: ButtonBorder;
-      color: Field;
-      color: FieldText;
-      color: Highlight;
-      color: HighlightText;
-      color: SelectedItem;
-      color: SelectedItemText;
-      color: Mark;
-      color: MarkText;
-      color: GrayText;
-    }
-
-    test-false-positives {
-      color: RandomWord;
-    }
-  `
-  const result = analyze(fixture)
-  const actual = result.values.colors
-  const expected = {
-    total: 17,
-    totalUnique: 17,
-    unique: {
-      Canvas: 1,
-      CanvasText: 1,
-      Linktext: 1,
-      VisitedText: 1,
-      ActiveText: 1,
-      ButtonFace: 1,
-      ButtonText: 1,
-      ButtonBorder: 1,
-      Field: 1,
-      FieldText: 1,
-      Highlight: 1,
-      HighlightText: 1,
-      SelectedItem: 1,
-      SelectedItemText: 1,
-      Mark: 1,
-      MarkText: 1,
-      GrayText: 1,
-    },
-    uniquenessRatio: 17 / 17,
-    itemsPerContext: {
-      color: {
-        total: 17,
-        totalUnique: 17,
-        unique: {
-          Canvas: 1,
-          CanvasText: 1,
-          Linktext: 1,
-          VisitedText: 1,
-          ActiveText: 1,
-          ButtonFace: 1,
-          ButtonText: 1,
-          ButtonBorder: 1,
-          Field: 1,
-          FieldText: 1,
-          Highlight: 1,
-          HighlightText: 1,
-          SelectedItem: 1,
-          SelectedItemText: 1,
-          Mark: 1,
-          MarkText: 1,
-          GrayText: 1,
-        },
-        uniquenessRatio: 19 / 19,
-      },
-    },
-    formats: {
-      total: 17,
-      totalUnique: 1,
-      unique: {
-        system: 17
-      },
-      uniquenessRatio: 1 / 17,
-    }
-  }
-
-  assert.equal(actual, expected)
-})
-
-Colors('insane color mode', () => {
-  const fixture = `
-    .color-insanity {
-      color: #7654CD;
-      color: rgb(46.27% 32.94% 80.39%);
-      color: lab(44.36% 36.05 -58.99);
-      color: color(xyz-d50 0.2005 0.14089 0.4472);
-    }
-  `
-
-  assert.not.throws(() => analyze(fixture))
-})
-
-Colors('Lists locations when unstable flag is set', () => {
-  let css = `
-    thing {
-      color: red;
-      color: #f00;
-      color: rgb(255, 0, 0);
-      background-color: red;
-    }
-  `
-  let actual = analyze(css, { useLocations: true })
-
-  assert.equal(actual.values.colors.uniqueWithLocations, {
-    'red': [
-      {
-        line: 3,
-        column: 14,
-        offset: 26,
-        length: 3,
-      },
-      {
-        line: 6,
-        column: 25,
-        offset: 103,
-        length: 3,
-      }
-    ],
-    '#f00': [
-      {
-        line: 4,
-        column: 14,
-        offset: 44,
-        length: 4,
-      }
-    ],
-    'rgb(255, 0, 0)': [
-      {
-        line: 5,
-        column: 14,
-        offset: 63,
-        length: 14,
-      }
-    ]
-  })
-})
-
-Colors.run()
\ No newline at end of file
diff --git a/src/values/colors.test.ts b/src/values/colors.test.ts
new file mode 100644
index 00000000..1ac3d1f2
--- /dev/null
+++ b/src/values/colors.test.ts
@@ -0,0 +1,1098 @@
+import { test } from 'vitest'
+import { expect } from 'vitest'
+import { analyze } from '../index.js'
+
+test('finds hex colors', () => {
+	const actual = analyze(`
+    test {
+      color: #000;
+      color: #1111;
+      color: #222222;
+      color: #33333333;
+    }
+
+    test-bg {
+      background: linear-gradient(90deg, #444 0, #444 100%);
+    }
+
+    test-box-shadow {
+      box-shadow: 0 0 0 #555;
+    }
+
+    test-outline-color {
+      outline-color: #666;
+    }
+
+    test-custom-property {
+      test: #777;
+    }
+
+    test-hex-casing {
+      casing: #AaBbCc;
+    }
+
+    #not-a-color {
+      margin: 0;
+    }
+  `).values.colors
+
+	const expected = {
+		total: 10,
+		totalUnique: 9,
+		unique: {
+			'#000': 1,
+			'#1111': 1,
+			'#222222': 1,
+			'#33333333': 1,
+			'#444': 2,
+			'#555': 1,
+			'#666': 1,
+			'#777': 1,
+			'#AaBbCc': 1,
+		},
+		uniquenessRatio: 9 / 10,
+		itemsPerContext: {
+			color: {
+				total: 4,
+				totalUnique: 4,
+				uniquenessRatio: 1,
+				unique: {
+					'#000': 1,
+					'#1111': 1,
+					'#222222': 1,
+					'#33333333': 1,
+				},
+			},
+			background: {
+				total: 2,
+				totalUnique: 1,
+				uniquenessRatio: 1 / 2,
+				unique: {
+					'#444': 2,
+				},
+			},
+			'box-shadow': {
+				total: 1,
+				totalUnique: 1,
+				uniquenessRatio: 1,
+				unique: {
+					'#555': 1,
+				},
+			},
+			'outline-color': {
+				total: 1,
+				totalUnique: 1,
+				uniquenessRatio: 1,
+				unique: {
+					'#666': 1,
+				},
+			},
+			test: {
+				total: 1,
+				totalUnique: 1,
+				uniquenessRatio: 1,
+				unique: {
+					'#777': 1,
+				},
+			},
+			casing: {
+				total: 1,
+				totalUnique: 1,
+				uniquenessRatio: 1,
+				unique: {
+					'#AaBbCc': 1,
+				},
+			},
+		},
+		formats: {
+			total: 10,
+			totalUnique: 4,
+			unique: {
+				hex3: 6,
+				hex4: 1,
+				hex6: 2,
+				hex8: 1,
+			},
+			uniquenessRatio: 4 / 10,
+		},
+	}
+	expect(actual).toEqual(expected)
+})
+
+test('Counts hex format correctly when combined with a browserhack', () => {
+	let actual = analyze(`
+    a {
+      color: #000\\9;
+    }
+  `)
+	let expected = {
+		total: 1,
+		totalUnique: 1,
+		unique: {
+			'#000\\9': 1,
+		},
+		uniquenessRatio: 1,
+		itemsPerContext: {
+			color: {
+				total: 1,
+				totalUnique: 1,
+				uniquenessRatio: 1,
+				unique: {
+					'#000\\9': 1,
+				},
+			},
+		},
+		formats: {
+			total: 1,
+			totalUnique: 1,
+			unique: {
+				hex3: 1,
+			},
+			uniquenessRatio: 1,
+		},
+	}
+	expect(actual.values.colors).toEqual(expected)
+})
+
+test('finds hsl(a) colors', () => {
+	const actual = analyze(`
+    test {
+      color: hsl(1, 20%, 30%);
+      color: hsl(1 20% 30% / 1);
+      color: Hsla(2, 20%, 30%, 0.5);
+    }
+
+    test-bg {
+      background: linear-gradient(90deg, hsl(3, 20%, 30%) 0, hsl(3, 20%, 30%) 100%);
+    }
+
+    test-box-shadow {
+      box-shadow: 0 0 0 hsl(4, 20%, 30%);
+    }
+
+    test-outline-color {
+      outline-color: hsl(5, 20%, 30%);
+    }
+
+    test-custom-property {
+      test: hsl(6, 20%, 30%);
+    }
+
+    test-notations {
+      color: hsl(30, 100%, 50%, 0.6);
+      color: hsla(30, 100%, 50%, 0.6);
+      color: hsl(30 100% 50% / 0.6);
+      color: hsla(30 100% 50% / 0.6);
+      color: hsl(30.0 100% 50% / 60%);
+      color: hsla(30.2 100% 50% / 60%);
+
+      /* Source: https://developer.mozilla.org/en-US/docs/Web/CSS/color_value#hsl_syntax_variations */
+      /* These examples all specify the same color: a lavender. */
+      color: hsl(270,60%,70%);
+      color: hsl(270, 60%, 70%);
+      color: hsl(270 60% 70%);
+      color: hsl(270deg, 60%, 70%);
+      color: hsl(4.71239rad, 60%, 70%);
+      color: hsl(.75turn, 60%, 70%);
+
+      /* These examples all specify the same color: a lavender that is 15% opaque. */
+      color: hsl(270, 60%, 50%, .15);
+      color: hsl(270, 60%, 50%, 15%);
+      color: hsl(270 60% 50% / .15);
+      color: hsl(270 60% 50% / 15%);
+    }
+  `).values.colors
+
+	const expected = {
+		total: 24,
+		totalUnique: 23,
+		unique: {
+			'hsl(1, 20%, 30%)': 1,
+			'hsl(1 20% 30% / 1)': 1,
+			'Hsla(2, 20%, 30%, 0.5)': 1,
+			'hsl(3, 20%, 30%)': 2,
+			'hsl(4, 20%, 30%)': 1,
+			'hsl(5, 20%, 30%)': 1,
+			'hsl(6, 20%, 30%)': 1,
+			'hsl(30, 100%, 50%, 0.6)': 1,
+			'hsla(30, 100%, 50%, 0.6)': 1,
+			'hsl(30 100% 50% / 0.6)': 1,
+			'hsla(30 100% 50% / 0.6)': 1,
+			'hsl(30.0 100% 50% / 60%)': 1,
+			'hsla(30.2 100% 50% / 60%)': 1,
+			'hsl(270,60%,70%)': 1,
+			'hsl(270, 60%, 70%)': 1,
+			'hsl(270 60% 70%)': 1,
+			'hsl(270deg, 60%, 70%)': 1,
+			'hsl(4.71239rad, 60%, 70%)': 1,
+			'hsl(.75turn, 60%, 70%)': 1,
+			'hsl(270, 60%, 50%, .15)': 1,
+			'hsl(270, 60%, 50%, 15%)': 1,
+			'hsl(270 60% 50% / .15)': 1,
+			'hsl(270 60% 50% / 15%)': 1,
+		},
+		uniquenessRatio: 23 / 24,
+		itemsPerContext: {
+			color: {
+				total: 19,
+				totalUnique: 19,
+				unique: {
+					'hsl(1, 20%, 30%)': 1,
+					'hsl(1 20% 30% / 1)': 1,
+					'Hsla(2, 20%, 30%, 0.5)': 1,
+					'hsl(30, 100%, 50%, 0.6)': 1,
+					'hsla(30, 100%, 50%, 0.6)': 1,
+					'hsl(30 100% 50% / 0.6)': 1,
+					'hsla(30 100% 50% / 0.6)': 1,
+					'hsl(30.0 100% 50% / 60%)': 1,
+					'hsla(30.2 100% 50% / 60%)': 1,
+					'hsl(270,60%,70%)': 1,
+					'hsl(270, 60%, 70%)': 1,
+					'hsl(270 60% 70%)': 1,
+					'hsl(270deg, 60%, 70%)': 1,
+					'hsl(4.71239rad, 60%, 70%)': 1,
+					'hsl(.75turn, 60%, 70%)': 1,
+					'hsl(270, 60%, 50%, .15)': 1,
+					'hsl(270, 60%, 50%, 15%)': 1,
+					'hsl(270 60% 50% / .15)': 1,
+					'hsl(270 60% 50% / 15%)': 1,
+				},
+				uniquenessRatio: 1,
+			},
+			background: {
+				total: 2,
+				totalUnique: 1,
+				unique: {
+					'hsl(3, 20%, 30%)': 2,
+				},
+				uniquenessRatio: 0.5,
+			},
+			'box-shadow': {
+				total: 1,
+				totalUnique: 1,
+				unique: {
+					'hsl(4, 20%, 30%)': 1,
+				},
+				uniquenessRatio: 1,
+			},
+			'outline-color': {
+				total: 1,
+				totalUnique: 1,
+				unique: {
+					'hsl(5, 20%, 30%)': 1,
+				},
+				uniquenessRatio: 1,
+			},
+			test: {
+				total: 1,
+				totalUnique: 1,
+				unique: {
+					'hsl(6, 20%, 30%)': 1,
+				},
+				uniquenessRatio: 1,
+			},
+		},
+		formats: {
+			total: 24,
+			totalUnique: 2,
+			unique: {
+				hsl: 20,
+				hsla: 4,
+			},
+			uniquenessRatio: 2 / 24,
+		},
+	}
+	expect(actual).toEqual(expected)
+})
+
+test('finds rgb(a) colors', () => {
+	const actual = analyze(`
+    test {
+      color: rgb(1, 1, 1);
+      color: rgba(2, 2, 2, 0.2);
+      color: RGBA(3, 3, 3, .3);
+      color: rgba(4,4,4,.4)
+    }
+
+    test-bg {
+      background: linear-gradient(90deg, rgb(5, 5, 5) 0, rgb(5, 5, 5) 100%);
+    }
+
+    test-box-shadow {
+      box-shadow: 0 0 0 rgb(6,6,6);
+    }
+
+    test-outline-color {
+      outline-color: rgb(7,7,7);
+    }
+
+    test-custom-property {
+      test: rgb(8,8,8);
+    }
+
+    /* Source: https://developer.mozilla.org/en-US/docs/Web/CSS/color */
+    test-notations {
+      color: rgb(34, 12, 64, 0.6);
+      color: rgba(34, 12, 64, 0.6);
+      color: rgb(34 12 64 / 0.6);
+      color: rgba(34 12 64 / 0.3);
+      color: rgb(34.0 12 64 / 60%);
+      color: rgba(34.6 12 64 / 30%);
+      color: rgba(255, 0, 153.6, 1);
+    }
+
+    /* https://developer.mozilla.org/en-US/docs/Web/CSS/color_value#rgb_transparency_variations */
+    test-exotic-numbers {
+      color: rgba(1e2, .5e1, .5e0, +.25e2%);
+    }
+  `).values.colors
+
+	const expected = {
+		total: 17,
+		totalUnique: 16,
+		unique: {
+			'rgb(1, 1, 1)': 1,
+			'rgba(2, 2, 2, 0.2)': 1,
+			'RGBA(3, 3, 3, .3)': 1,
+			'rgba(4,4,4,.4)': 1,
+			'rgb(5, 5, 5)': 2,
+			'rgb(6,6,6)': 1,
+			'rgb(7,7,7)': 1,
+			'rgb(8,8,8)': 1,
+			'rgb(34, 12, 64, 0.6)': 1,
+			'rgba(34, 12, 64, 0.6)': 1,
+			'rgb(34 12 64 / 0.6)': 1,
+			'rgba(34 12 64 / 0.3)': 1,
+			'rgb(34.0 12 64 / 60%)': 1,
+			'rgba(34.6 12 64 / 30%)': 1,
+			'rgba(255, 0, 153.6, 1)': 1,
+			'rgba(1e2, .5e1, .5e0, +.25e2%)': 1,
+		},
+		uniquenessRatio: 16 / 17,
+		itemsPerContext: {
+			color: {
+				total: 12,
+				totalUnique: 12,
+				unique: {
+					'rgb(1, 1, 1)': 1,
+					'rgba(2, 2, 2, 0.2)': 1,
+					'RGBA(3, 3, 3, .3)': 1,
+					'rgba(4,4,4,.4)': 1,
+					'rgb(34, 12, 64, 0.6)': 1,
+					'rgba(34, 12, 64, 0.6)': 1,
+					'rgb(34 12 64 / 0.6)': 1,
+					'rgba(34 12 64 / 0.3)': 1,
+					'rgb(34.0 12 64 / 60%)': 1,
+					'rgba(34.6 12 64 / 30%)': 1,
+					'rgba(255, 0, 153.6, 1)': 1,
+					'rgba(1e2, .5e1, .5e0, +.25e2%)': 1,
+				},
+				uniquenessRatio: 1,
+			},
+			background: {
+				total: 2,
+				totalUnique: 1,
+				unique: {
+					'rgb(5, 5, 5)': 2,
+				},
+				uniquenessRatio: 0.5,
+			},
+			'box-shadow': {
+				total: 1,
+				totalUnique: 1,
+				unique: {
+					'rgb(6,6,6)': 1,
+				},
+				uniquenessRatio: 1,
+			},
+			'outline-color': {
+				total: 1,
+				totalUnique: 1,
+				unique: {
+					'rgb(7,7,7)': 1,
+				},
+				uniquenessRatio: 1,
+			},
+			test: {
+				total: 1,
+				totalUnique: 1,
+				unique: {
+					'rgb(8,8,8)': 1,
+				},
+				uniquenessRatio: 1,
+			},
+		},
+		formats: {
+			total: 17,
+			totalUnique: 2,
+			unique: {
+				rgb: 9,
+				rgba: 8,
+			},
+			uniquenessRatio: 2 / 17,
+		},
+	}
+	expect(actual).toEqual(expected)
+})
+
+test('finds LCH() colors', () => {
+	const actual = analyze(`
+    .lch {
+      /* Source: https://developer.mozilla.org/en-US/docs/Web/CSS/color_value/lch() */
+      color: lch(29.2345% 44.2 27);
+      color: lch(52.2345% 72.2 56.2);
+
+      /* Capitalisation */
+      color: LCH(29.2345% 44.2 27);
+      color: Lch(29.2345% 44.2 27);
+
+      /* Opacity notations */
+      color: lch(52.2345% 72.2 56.2 / 1);
+      color: lch(52.2345% 72.2 56.2 / .5);
+      color: lch(52.2345% 72.2 56.2 / 0.5);
+      color: lch(52.2345% 72.2 56.2 / 50%);
+    }
+  `)
+	const expected = {
+		total: 8,
+		totalUnique: 8,
+		unique: {
+			'lch(29.2345% 44.2 27)': 1,
+			'lch(52.2345% 72.2 56.2)': 1,
+
+			/* Capitalisation */
+			'LCH(29.2345% 44.2 27)': 1,
+			'Lch(29.2345% 44.2 27)': 1,
+
+			/* Opacity notations */
+			'lch(52.2345% 72.2 56.2 / 1)': 1,
+			'lch(52.2345% 72.2 56.2 / .5)': 1,
+			'lch(52.2345% 72.2 56.2 / 0.5)': 1,
+			'lch(52.2345% 72.2 56.2 / 50%)': 1,
+		},
+		uniquenessRatio: 1,
+		itemsPerContext: {
+			color: {
+				total: 8,
+				totalUnique: 8,
+				unique: {
+					'lch(29.2345% 44.2 27)': 1,
+					'lch(52.2345% 72.2 56.2)': 1,
+					'LCH(29.2345% 44.2 27)': 1,
+					'Lch(29.2345% 44.2 27)': 1,
+					'lch(52.2345% 72.2 56.2 / 1)': 1,
+					'lch(52.2345% 72.2 56.2 / .5)': 1,
+					'lch(52.2345% 72.2 56.2 / 0.5)': 1,
+					'lch(52.2345% 72.2 56.2 / 50%)': 1,
+				},
+				uniquenessRatio: 1,
+			},
+		},
+		formats: {
+			total: 8,
+			totalUnique: 1,
+			unique: {
+				lch: 8,
+			},
+			uniquenessRatio: 1 / 8,
+		},
+	}
+
+	expect(actual.values.colors).toEqual(expected)
+})
+
+test('finds LAB() colors', () => {
+	const actual = analyze(`
+    .lch {
+      /* Source: https://drafts.csswg.org/css-color/#specifying-lab-lch */
+      color: lab(52.2345% 40.1645 59.9971);
+      color: lab(60.2345% -5.3654 58.956);
+      color: lab(62.2345% -34.9638 47.7721);
+      color: lab(67.5345% -8.6911 -41.6019);
+
+      /* Capitalisation */
+      color: lab(29.2345% 39.3825 20.0664);
+      color: Lab(29.2345% 39.3825 20.0664);
+      color: LAB(29.2345% 39.3825 20.0664);
+
+      /* Opacity notations */
+      color: lab(52.2345% 40.1645 59.9971 / 0);
+      color: lab(52.2345% 40.1645 59.9971 / .5);
+      color: lab(52.2345% 40.1645 59.9971 / 0.5);
+      color: lab(52.2345% 40.1645 59.9971 / 50%);
+    }
+  `)
+	const expected = {
+		total: 11,
+		totalUnique: 11,
+		unique: {
+			'lab(52.2345% 40.1645 59.9971)': 1,
+			'lab(60.2345% -5.3654 58.956)': 1,
+			'lab(62.2345% -34.9638 47.7721)': 1,
+			'lab(67.5345% -8.6911 -41.6019)': 1,
+
+			/* Capitalisation */
+			'lab(29.2345% 39.3825 20.0664)': 1,
+			'Lab(29.2345% 39.3825 20.0664)': 1,
+			'LAB(29.2345% 39.3825 20.0664)': 1,
+
+			/* Opacity notations */
+			'lab(52.2345% 40.1645 59.9971 / 0)': 1,
+			'lab(52.2345% 40.1645 59.9971 / .5)': 1,
+			'lab(52.2345% 40.1645 59.9971 / 0.5)': 1,
+			'lab(52.2345% 40.1645 59.9971 / 50%)': 1,
+		},
+		uniquenessRatio: 1,
+		itemsPerContext: {
+			color: {
+				total: 11,
+				totalUnique: 11,
+				unique: {
+					'lab(52.2345% 40.1645 59.9971)': 1,
+					'lab(60.2345% -5.3654 58.956)': 1,
+					'lab(62.2345% -34.9638 47.7721)': 1,
+					'lab(67.5345% -8.6911 -41.6019)': 1,
+					'lab(29.2345% 39.3825 20.0664)': 1,
+					'Lab(29.2345% 39.3825 20.0664)': 1,
+					'LAB(29.2345% 39.3825 20.0664)': 1,
+					'lab(52.2345% 40.1645 59.9971 / 0)': 1,
+					'lab(52.2345% 40.1645 59.9971 / .5)': 1,
+					'lab(52.2345% 40.1645 59.9971 / 0.5)': 1,
+					'lab(52.2345% 40.1645 59.9971 / 50%)': 1,
+				},
+				uniquenessRatio: 1,
+			},
+		},
+		formats: {
+			total: 11,
+			totalUnique: 1,
+			unique: {
+				lab: 11,
+			},
+			uniquenessRatio: 1 / 11,
+		},
+	}
+
+	expect(actual.values.colors).toEqual(expected)
+})
+
+test('finds hwb() colors', () => {
+	const actual = analyze(`
+    .hwb {
+      color: hwb(194 0% 0%);
+      color: hwb(194, 0%, 0%);
+
+      color: Hwb(194 0% 0%);
+      color: HWB(194 0% 0%);
+
+      color: hwb(194 0% 0% / .5);
+      color: hwb(194 0% 0% / 0.5);
+      color: hwb(194 0% 0% / 50%);
+    }
+  `)
+	const expected = {
+		total: 7,
+		totalUnique: 7,
+		uniquenessRatio: 1,
+		unique: {
+			'hwb(194 0% 0%)': 1,
+			'hwb(194, 0%, 0%)': 1,
+
+			'Hwb(194 0% 0%)': 1,
+			'HWB(194 0% 0%)': 1,
+
+			'hwb(194 0% 0% / .5)': 1,
+			'hwb(194 0% 0% / 0.5)': 1,
+			'hwb(194 0% 0% / 50%)': 1,
+		},
+		itemsPerContext: {
+			color: {
+				total: 7,
+				totalUnique: 7,
+				unique: {
+					'hwb(194 0% 0%)': 1,
+					'hwb(194, 0%, 0%)': 1,
+					'Hwb(194 0% 0%)': 1,
+					'HWB(194 0% 0%)': 1,
+					'hwb(194 0% 0% / .5)': 1,
+					'hwb(194 0% 0% / 0.5)': 1,
+					'hwb(194 0% 0% / 50%)': 1,
+				},
+				uniquenessRatio: 1,
+			},
+		},
+		formats: {
+			total: 7,
+			totalUnique: 1,
+			unique: {
+				hwb: 7,
+			},
+			uniquenessRatio: 1 / 7,
+		},
+	}
+
+	expect(actual.values.colors).toEqual(expected)
+})
+
+test('finds color() colors', () => {
+	const actual = analyze(`
+    .colors {
+      color: color(rec2020 0.42053 0.979780 0.00579);
+      color: color(display-p3 -0.6112 1.0079 -0.2192);
+      color: color(profoto-rgb 0.4835 0.9167 0.2188);
+      color: color(xyz-d50 0.2005 0.14089 0.4472);
+    }
+  `)
+	const expected = {
+		total: 4,
+		totalUnique: 4,
+		unique: {
+			'color(rec2020 0.42053 0.979780 0.00579)': 1,
+			'color(display-p3 -0.6112 1.0079 -0.2192)': 1,
+			'color(profoto-rgb 0.4835 0.9167 0.2188)': 1,
+			'color(xyz-d50 0.2005 0.14089 0.4472)': 1,
+		},
+		uniquenessRatio: 1,
+		itemsPerContext: {
+			color: {
+				total: 4,
+				totalUnique: 4,
+				unique: {
+					'color(rec2020 0.42053 0.979780 0.00579)': 1,
+					'color(display-p3 -0.6112 1.0079 -0.2192)': 1,
+					'color(profoto-rgb 0.4835 0.9167 0.2188)': 1,
+					'color(xyz-d50 0.2005 0.14089 0.4472)': 1,
+				},
+				uniquenessRatio: 1,
+			},
+		},
+		formats: {
+			total: 4,
+			totalUnique: 1,
+			unique: {
+				color: 4,
+			},
+			uniquenessRatio: 1 / 4,
+		},
+	}
+
+	expect(actual.values.colors).toEqual(expected)
+})
+
+test('finds color keywords', () => {
+	const actual = analyze(`
+    test {
+      outline: 1px solid tomato;
+      border-color: Aqua;
+      outline-color: whitesmoke;
+      background: linear-gradient(90deg, purple 0, purple 100%);
+    }
+  `).values.colors
+	const expected = {
+		total: 5,
+		totalUnique: 4,
+		unique: {
+			tomato: 1,
+			Aqua: 1,
+			whitesmoke: 1,
+			purple: 2,
+		},
+		uniquenessRatio: 4 / 5,
+		itemsPerContext: {
+			outline: {
+				total: 1,
+				totalUnique: 1,
+				unique: {
+					tomato: 1,
+				},
+				uniquenessRatio: 1,
+			},
+			'border-color': {
+				total: 1,
+				totalUnique: 1,
+				unique: {
+					Aqua: 1,
+				},
+				uniquenessRatio: 1,
+			},
+			'outline-color': {
+				total: 1,
+				totalUnique: 1,
+				unique: {
+					whitesmoke: 1,
+				},
+				uniquenessRatio: 1,
+			},
+			background: {
+				total: 2,
+				totalUnique: 1,
+				unique: {
+					purple: 2,
+				},
+				uniquenessRatio: 0.5,
+			},
+		},
+		formats: {
+			total: 5,
+			totalUnique: 1,
+			unique: {
+				named: 5,
+			},
+			uniquenessRatio: 1 / 5,
+		},
+	}
+	expect(actual).toEqual(expected)
+})
+
+test('does not report false positives for color keywords', () => {
+	const actual = analyze(`
+    test {
+      /* Not a blue keyword */
+      background: url(icon-blue.png), url(blue-icon.png), url(blue_icon.png), url(icon_blue.png);
+
+      /* Not a hex color */
+      background-image: url(#footer-logo-text-linear-gradient);
+
+      /* Not the white color keyword */
+      white-space: nowrap;
+
+      /* Not the linen color keyword */
+      counter-increment: lineNo;
+
+      /* Not the gray keyword */
+      -moz-osx-font-smoothing: grayscale;
+
+      /* Not the black color keyword */
+      font-family: Arial Black, Arial Bold, Gadget, sans-serif;
+      font: 1em/1 Black;
+
+      /* not a color keyword */
+      -ms-overflow-style: scrollbar;
+    }
+  `).values.colors
+	const expected = {
+		total: 0,
+		totalUnique: 0,
+		unique: {},
+		uniquenessRatio: 0,
+		itemsPerContext: {},
+		formats: {
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+		},
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+// Source: https://gist.github.com/lahmatiy/84c7fd877a78e561cac57e59e142c9e3
+test.skip('ignores color names that are not actual colors', () => {
+	const fixture = `
+    test {
+      animation: red; /* it's not a color but an animation name */
+      unknown-property: blue; /* don't match value as a color when property is unknown */
+    }
+  `
+	const actual = analyze(fixture).values.colors
+	const expected = {
+		total: 0,
+		totalUnique: 0,
+		unique: {},
+		uniquenessRatio: 0,
+		itemsPerContext: {},
+		formats: {
+			total: 0,
+			totalUnique: 0,
+			unique: {},
+			uniquenessRatio: 0,
+		},
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('finds colors in var() as fallback values', () => {
+	const fixture = `
+    test {
+      --main: #aaa;
+      color: var(--main, #eee);
+
+      /* from github */
+      box-shadow: 0 3px 12px var(--color-fade-black-15), 0 0 1px rgba(27, 31, 35, .2);
+      text-shadow: 0 0 var(--main, var(--sec, #000));
+    }
+  `
+	const result = analyze(fixture)
+	const actual = result.values.colors
+	const expected = {
+		total: 4,
+		totalUnique: 4,
+		unique: {
+			'#aaa': 1,
+			'#eee': 1,
+			'rgba(27, 31, 35, .2)': 1,
+			'#000': 1,
+		},
+		uniquenessRatio: 4 / 4,
+		itemsPerContext: {
+			'--main': {
+				total: 1,
+				totalUnique: 1,
+				unique: {
+					'#aaa': 1,
+				},
+				uniquenessRatio: 1,
+			},
+			color: {
+				total: 1,
+				totalUnique: 1,
+				unique: {
+					'#eee': 1,
+				},
+				uniquenessRatio: 1,
+			},
+			'box-shadow': {
+				total: 1,
+				totalUnique: 1,
+				unique: {
+					'rgba(27, 31, 35, .2)': 1,
+				},
+				uniquenessRatio: 1,
+			},
+			'text-shadow': {
+				total: 1,
+				totalUnique: 1,
+				unique: {
+					'#000': 1,
+				},
+				uniquenessRatio: 1,
+			},
+		},
+		formats: {
+			total: 4,
+			totalUnique: 2,
+			unique: {
+				hex3: 3,
+				rgba: 1,
+			},
+			uniquenessRatio: 2 / 4,
+		},
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('ignores CSS keywords', () => {
+	const fixture = `
+    testColorKeywords {
+      color: currentColor;
+      color: currentcolor;
+      color: inherit;
+      color: unset;
+      color: initial;
+      color: transparent;
+      color: revert;
+      color: revert-layer;
+      background: none;
+    }
+
+    positive {
+      background: none 0px 0px repeat scroll rgb(0, 0, 0);
+    }
+  `
+	const actual = analyze(fixture).values.colors
+	const expected = {
+		total: 4,
+		totalUnique: 4,
+		unique: {
+			currentColor: 1,
+			currentcolor: 1,
+			transparent: 1,
+			'rgb(0, 0, 0)': 1,
+		},
+		uniquenessRatio: 4 / 4,
+		itemsPerContext: {
+			color: {
+				total: 3,
+				totalUnique: 3,
+				unique: {
+					currentColor: 1,
+					currentcolor: 1,
+					transparent: 1,
+				},
+				uniquenessRatio: 3 / 3,
+			},
+			background: {
+				total: 1,
+				totalUnique: 1,
+				unique: {
+					'rgb(0, 0, 0)': 1,
+				},
+				uniquenessRatio: 1,
+			},
+		},
+		formats: {
+			total: 4,
+			totalUnique: 3,
+			unique: {
+				currentcolor: 2,
+				transparent: 1,
+				rgb: 1,
+			},
+			uniquenessRatio: 3 / 4,
+		},
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+// https://drafts.csswg.org/css-color/#css-system-colors
+test('finds System Colors', () => {
+	const fixture = `
+    color: test-system-colors {
+      color: Canvas;
+      color: CanvasText;
+      color: Linktext;
+      color: VisitedText;
+      color: ActiveText;
+      color: ButtonFace;
+      color: ButtonText;
+      color: ButtonBorder;
+      color: Field;
+      color: FieldText;
+      color: Highlight;
+      color: HighlightText;
+      color: SelectedItem;
+      color: SelectedItemText;
+      color: Mark;
+      color: MarkText;
+      color: GrayText;
+    }
+
+    test-false-positives {
+      color: RandomWord;
+    }
+  `
+	const result = analyze(fixture)
+	const actual = result.values.colors
+	const expected = {
+		total: 17,
+		totalUnique: 17,
+		unique: {
+			Canvas: 1,
+			CanvasText: 1,
+			Linktext: 1,
+			VisitedText: 1,
+			ActiveText: 1,
+			ButtonFace: 1,
+			ButtonText: 1,
+			ButtonBorder: 1,
+			Field: 1,
+			FieldText: 1,
+			Highlight: 1,
+			HighlightText: 1,
+			SelectedItem: 1,
+			SelectedItemText: 1,
+			Mark: 1,
+			MarkText: 1,
+			GrayText: 1,
+		},
+		uniquenessRatio: 17 / 17,
+		itemsPerContext: {
+			color: {
+				total: 17,
+				totalUnique: 17,
+				unique: {
+					Canvas: 1,
+					CanvasText: 1,
+					Linktext: 1,
+					VisitedText: 1,
+					ActiveText: 1,
+					ButtonFace: 1,
+					ButtonText: 1,
+					ButtonBorder: 1,
+					Field: 1,
+					FieldText: 1,
+					Highlight: 1,
+					HighlightText: 1,
+					SelectedItem: 1,
+					SelectedItemText: 1,
+					Mark: 1,
+					MarkText: 1,
+					GrayText: 1,
+				},
+				uniquenessRatio: 19 / 19,
+			},
+		},
+		formats: {
+			total: 17,
+			totalUnique: 1,
+			unique: {
+				system: 17,
+			},
+			uniquenessRatio: 1 / 17,
+		},
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('insane color mode', () => {
+	const fixture = `
+    .color-insanity {
+      color: #7654CD;
+      color: rgb(46.27% 32.94% 80.39%);
+      color: lab(44.36% 36.05 -58.99);
+      color: color(xyz-d50 0.2005 0.14089 0.4472);
+    }
+  `
+
+	expect(() => analyze(fixture)).not.toThrow()
+})
+
+test('Lists locations when unstable flag is set', () => {
+	let css = `
+    thing {
+      color: red;
+      color: #f00;
+      color: rgb(255, 0, 0);
+      background-color: red;
+    }
+  `
+	let actual = analyze(css, { useLocations: true })
+
+	expect(actual.values.colors.uniqueWithLocations).toEqual({
+		red: [
+			{
+				line: 3,
+				column: 14,
+				offset: 26,
+				length: 3,
+			},
+			{
+				line: 6,
+				column: 25,
+				offset: 103,
+				length: 3,
+			},
+		],
+		'#f00': [
+			{
+				line: 4,
+				column: 14,
+				offset: 44,
+				length: 4,
+			},
+		],
+		'rgb(255, 0, 0)': [
+			{
+				line: 5,
+				column: 14,
+				offset: 63,
+				length: 14,
+			},
+		],
+	})
+})
diff --git a/src/values/colors.ts b/src/values/colors.ts
new file mode 100644
index 00000000..899a7b77
--- /dev/null
+++ b/src/values/colors.ts
@@ -0,0 +1,185 @@
+import { KeywordSet } from '../keyword-set.js'
+
+export const namedColors = new KeywordSet([
+	// CSS Named Colors
+	// Spec: https://drafts.csswg.org/css-color/#named-colors
+
+	// Heuristic: popular names first for quick finding in set.has()
+	// See: https://docs.google.com/spreadsheets/d/1OU8ahxC5oYU8VRryQs9BzHToaXcOntVlh6KUHjm15G4/edit#gid=2096495459
+	'white',
+	'black',
+	'red',
+	'gray',
+	'silver',
+	'grey',
+	'green',
+	'orange',
+	'blue',
+	'dimgray',
+	'whitesmoke',
+	'lightgray',
+	'lightgrey',
+	'yellow',
+	'gold',
+	'pink',
+	'gainsboro',
+	'magenta',
+	'purple',
+	'darkgray',
+	'navy',
+	'darkred',
+	'teal',
+	'maroon',
+	'darkgrey',
+	'tomato',
+	'darkorange',
+	'brown',
+	'crimson',
+	'lightyellow',
+	'slategray',
+	'salmon',
+	'lightgreen',
+	'lightblue',
+	'orangered',
+	'aliceblue',
+	'dodgerblue',
+	'lime',
+	'darkblue',
+	'darkgoldenrod',
+	'skyblue',
+	'royalblue',
+	'darkgreen',
+	'ivory',
+	'olive',
+	'aqua',
+	'turquoise',
+	'cyan',
+	'khaki',
+	'beige',
+	'snow',
+	'ghostwhite',
+	'limegreen',
+	'coral',
+	'dimgrey',
+	'hotpink',
+	'midnightblue',
+	'firebrick',
+	'indigo',
+	'wheat',
+	'mediumblue',
+	'lightpink',
+	'plum',
+	'azure',
+	'violet',
+	'lavender',
+	'deepskyblue',
+	'darkslategrey',
+	'goldenrod',
+	'cornflowerblue',
+	'lightskyblue',
+	'indianred',
+	'yellowgreen',
+	'saddlebrown',
+	'palegreen',
+	'bisque',
+	'tan',
+	'antiquewhite',
+	'steelblue',
+	'forestgreen',
+	'fuchsia',
+	'mediumaquamarine',
+	'seagreen',
+	'sienna',
+	'deeppink',
+	'mediumseagreen',
+	'peru',
+	'greenyellow',
+	'lightgoldenrodyellow',
+	'orchid',
+	'cadetblue',
+	'navajowhite',
+	'lightsteelblue',
+	'slategrey',
+	'linen',
+	'lightseagreen',
+	'darkcyan',
+	'lightcoral',
+	'aquamarine',
+	'blueviolet',
+	'cornsilk',
+	'lightsalmon',
+	'chocolate',
+	'lightslategray',
+	'floralwhite',
+	'darkturquoise',
+	'darkslategray',
+	'rebeccapurple',
+	'burlywood',
+	'chartreuse',
+	'lightcyan',
+	'lemonchiffon',
+	'palevioletred',
+	'darkslateblue',
+	'mediumpurple',
+	'lawngreen',
+	'slateblue',
+	'darkseagreen',
+	'blanchedalmond',
+	'mistyrose',
+	'darkolivegreen',
+	'seashell',
+	'olivedrab',
+	'peachpuff',
+	'darkviolet',
+	'powderblue',
+	'darkmagenta',
+	'lightslategrey',
+	'honeydew',
+	'palegoldenrod',
+	'darkkhaki',
+	'oldlace',
+	'mintcream',
+	'sandybrown',
+	'mediumturquoise',
+	'papayawhip',
+	'paleturquoise',
+	'mediumvioletred',
+	'thistle',
+	'springgreen',
+	'moccasin',
+	'rosybrown',
+	'lavenderblush',
+	'mediumslateblue',
+	'darkorchid',
+	'mediumorchid',
+	'darksalmon',
+	'mediumspringgreen',
+])
+
+export const systemColors = new KeywordSet([
+	// CSS System Colors
+	// Spec: https://drafts.csswg.org/css-color/#css-system-colors
+	'accentcolor',
+	'accentcolortext',
+	'activetext',
+	'buttonborder',
+	'buttonface',
+	'buttontext',
+	'canvas',
+	'canvastext',
+	'field',
+	'fieldtext',
+	'graytext',
+	'highlight',
+	'highlighttext',
+	'linktext',
+	'mark',
+	'marktext',
+	'selecteditem',
+	'selecteditemtext',
+	'visitedtext',
+])
+
+export const colorFunctions = new KeywordSet(['rgba', 'rgb', 'hsla', 'hsl', 'oklch', 'color', 'hwb', 'lch', 'lab', 'oklab'])
+
+export const colorKeywords = new KeywordSet(['transparent', 'currentcolor'])
diff --git a/src/values/complexity.test.js b/src/values/complexity.test.ts
similarity index 74%
rename from src/values/complexity.test.js
rename to src/values/complexity.test.ts
index 3cc48052..ea622ccf 100644
--- a/src/values/complexity.test.js
+++ b/src/values/complexity.test.ts
@@ -1,9 +1,7 @@
-import { suite } from 'uvu';
-import * as assert from 'uvu/assert';
+import { test } from 'vitest'
+import { expect } from 'vitest'
 import { analyze } from '../index.js'
 
-const test = suite('Value complexity')
-
 test('calculates value complexity', () => {
 	const fixture = `
     a {
@@ -24,7 +22,5 @@ test('calculates value complexity', () => {
 		sum: 10,
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
-
-test.run()
diff --git a/src/values/destructure-font-shorthand.js b/src/values/destructure-font-shorthand.ts
similarity index 66%
rename from src/values/destructure-font-shorthand.js
rename to src/values/destructure-font-shorthand.ts
index 5e6903a4..7f875ec9 100644
--- a/src/values/destructure-font-shorthand.js
+++ b/src/values/destructure-font-shorthand.ts
@@ -1,15 +1,9 @@
 import { KeywordSet } from '../keyword-set.js'
 import { keywords } from './values.js'
 import { Identifier, Nr, Operator } from '../css-tree-node-types.js'
+import type { CssNode, Value } from 'css-tree'
 
-const SYSTEM_FONTS = new KeywordSet([
-	'caption',
-	'icon',
-	'menu',
-	'message-box',
-	'small-caption',
-	'status-bar',
-])
+const SYSTEM_FONTS = new KeywordSet(['caption', 'icon', 'menu', 'message-box', 'small-caption', 'status-bar'])
 
 const SIZE_KEYWORDS = new KeywordSet([
 	/* <absolute-size> values */
@@ -29,7 +23,7 @@ const SIZE_KEYWORDS = new KeywordSet([
 const COMMA = 44 // ','.charCodeAt(0) === 44
 const SLASH = 47 // '/'.charCodeAt(0) === 47
 
-export function isSystemFont(node) {
+export function isSystemFont(node: Value) {
 	let firstChild = node.children.first
 	if (firstChild === null) return false
 	return firstChild.type === Identifier && SYSTEM_FONTS.has(firstChild.name)
@@ -39,16 +33,17 @@ export function isSystemFont(node) {
  * @param {import('css-tree').Value} value
  * @param {*} stringifyNode
  */
-export function destructure(value, stringifyNode, cb) {
-	/** @type {Array<import('css-tree').CssNode | undefined>} */
-	let font_family = [,]
-	/** @type {string | undefined} */
-	let font_size
-	/** @type {string | undefined} */
-	let line_height
+export function destructure(
+	value: Value,
+	stringifyNode: (node: CssNode) => string,
+	cb: ({ type, value }: { type: string; value: string }) => void,
+) {
+	let font_family: (CssNode | undefined)[] = [undefined, undefined]
+	let font_size: string | undefined
+	let line_height: string | undefined
 
 	// Bail out if the value is a single var()
-	if (value.children.first.type === 'Function' && value.children.first.name.toLowerCase() === 'var') {
+	if (value.children.first!.type === 'Function' && value.children.first.name.toLowerCase() === 'var') {
 		return null
 	}
 
@@ -76,12 +71,7 @@ export function destructure(value, stringifyNode, cb) {
 		}
 
 		// any node that's followed by ',' is a font-family
-		if (
-			next &&
-			next.type === Operator &&
-			next.value.charCodeAt(0) === COMMA &&
-			!font_family[0]
-		) {
+		if (next && next.type === Operator && next.value.charCodeAt(0) === COMMA && !font_family[0]) {
 			font_family[0] = node
 
 			if (!font_size && prev) {
@@ -120,20 +110,24 @@ export function destructure(value, stringifyNode, cb) {
 		}
 	})
 
-	let family = (font_family[0] || font_family[1])
-		? stringifyNode({
-			loc: {
-				start: {
-					offset: (font_family[0] || font_family[1]).loc.start.offset,
-				},
-				end: {
-					// Either the node we detected as the last node, or the end of the whole value
-					// It's never 0 because the first node is always a font-size or font-style
-					offset: font_family[1]?.loc.end.offset || value.loc.end.offset,
-				},
-			},
-		})
-		: null
+	let family =
+		font_family[0] || font_family[1]
+			? stringifyNode({
+					loc: {
+						// @ts-expect-error TODO: fix this
+						start: {
+							// @ts-expect-error TODO: fix this
+							offset: (font_family[0] || font_family[1]).loc!.start.offset,
+						},
+						// @ts-expect-error TODO: fix this
+						end: {
+							// Either the node we detected as the last node, or the end of the whole value
+							// It's never 0 because the first node is always a font-size or font-style
+							offset: font_family[1]?.loc!.end.offset || value.loc!.end.offset,
+						},
+					},
+				})
+			: null
 
 	return {
 		font_size,
diff --git a/src/values/font-families.test.js b/src/values/font-families.test.js
deleted file mode 100644
index 14abcb06..00000000
--- a/src/values/font-families.test.js
+++ /dev/null
@@ -1,172 +0,0 @@
-import { suite } from 'uvu';
-import * as assert from 'uvu/assert';
-import { analyze } from '../index.js'
-
-const FontFamilies = suite('FontFamilies')
-
-FontFamilies('recognizes a font-family', () => {
-  const fixture = `
-    test {
-      font-family: "Droid Sans", serif;
-      font-family: sans-serif;
-      font-family: "Arial Black", 'Arial Bold', Gadget, sans-serif;
-      font-family: Brush Script MT, cursive;
-      font-family: monospace;
-      font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;
-      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
-
-      /* Unrelated */
-      color: brown;
-      font-size: 12px;
-    }
-  `
-  const actual = analyze(fixture).values.fontFamilies
-  const expected = {
-    total: 7,
-    totalUnique: 7,
-    unique: {
-      '"Droid Sans", serif': 1,
-      'sans-serif': 1,
-      [`"Arial Black", 'Arial Bold', Gadget, sans-serif`]: 1,
-      'Brush Script MT, cursive': 1,
-      'monospace': 1,
-      'Consolas, "Liberation Mono", Menlo, Courier, monospace': 1,
-      '-apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"': 1,
-    },
-    uniquenessRatio: 7 / 7
-  }
-
-  assert.equal(actual, expected)
-})
-
-FontFamilies('extracts the `font` shorthand', () => {
-  const fixture = `
-    test {
-      font: large 'Noto Sans';
-      font: normal normal 1em/1 "Source Sans Pro", serif;
-      font: normal normal 1.2em serif;
-      font: 400 1.3em/1 serif;
-      font: 1em / 1 serif;
-      font: 1em/ 1 serif;
-      font: 1em /1 serif;
-      font: normal normal 11px/1.5 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
-      font: 11px Consolas, "Liberation Mono", Menlo, Courier, monospace;
-      font: 0/0 a; /* As generated by some css minifiers */
-      font: 1.2em/1.2em; /* Found in indiatimes.com */
-      font: 12px var(--fontStack-monospace, ui-monospace, SFMono-Regular, SF Mono, Menlo, Consolas, Liberation Mono, monospace); /* From github.com */
-
-      /* Unrelated */
-      color: brown;
-      font-size: 123456789px;
-    }
-  `
-  const actual = analyze(fixture).values.fontFamilies
-  const expected = {
-    total: 12,
-    totalUnique: 8,
-    unique: {
-      [`'Noto Sans'`]: 1,
-      '"Source Sans Pro", serif': 1,
-      'serif': 5,
-      '-apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"': 1,
-      'Consolas, "Liberation Mono", Menlo, Courier, monospace': 1,
-      'a': 1,
-      'var(--fontStack-monospace, ui-monospace, SFMono-Regular, SF Mono, Menlo, Consolas, Liberation Mono, monospace)': 1,
-      // This entry exists due to a ??bug?? in CSSTree, but it's better than not counting the value above this as well
-      'ui-monospace, SFMono-Regular, SF Mono, Menlo, Consolas, Liberation Mono, monospace': 1,
-    },
-    uniquenessRatio: 8 / 12
-  }
-  assert.equal(actual, expected)
-})
-
-FontFamilies('does not crash on `12px var(...)', () => {
-  const fixture = `
-    test {
-      font: 12px var(--fontStack-monospace, ui-monospace, SFMono-Regular, SF Mono, Menlo, Consolas, Liberation Mono, monospace);
-    }
-  `
-  assert.not.throws(() => {
-    analyze(fixture).values.fontFamilies
-  })
-})
-
-FontFamilies('does not crash on 14px "Inter Var", sans-serif, 700', () => {
-  const fixture = `
-    test {
-      font: 14px "Inter Var", sans-serif, 700;
-    }
-  `
-  assert.not.throws(() => {
-    analyze(fixture).values.fontFamilies
-  })
-  let { fontFamilies, fontSizes } = analyze(fixture).values
-  assert.equal(fontFamilies.unique, {
-    '"Inter Var", sans-serif, 700': 1,
-  })
-  assert.equal(fontSizes.unique, {
-    '14px': 1,
-  })
-})
-
-FontFamilies('does not crash on var(--x, )', () => {
-  const fixture = `
-    a {
-      font: var(--x, );
-    }
-  `
-  assert.not.throws(() => {
-    analyze(fixture).values.fontFamilies
-  })
-})
-
-FontFamilies('handles system fonts', () => {
-  // Source: https://drafts.csswg.org/css-fonts-3/#font-prop
-  const fixture = `
-    test {
-      font: menu;        /* use the font settings for system menus */
-      font: large menu;  /* use a font family named "menu" */
-    }
-  `
-  const actual = analyze(fixture).values.fontFamilies
-  const expected = {
-    total: 1,
-    totalUnique: 1,
-    unique: {
-      'menu': 1
-    },
-    uniquenessRatio: 1 / 1
-  }
-
-  assert.equal(actual, expected)
-})
-
-FontFamilies('ignores keywords and global values', () => {
-  const fixture = `
-    test {
-      /* Global values */
-      font-family: inherit;
-      font-family: initial;
-      font-family: revert;
-      font-family: revert-layer;
-      font-family: unset;
-
-      font: inherit;
-      font: initial;
-      font: revert;
-      font: revert-layer;
-      font: unset;
-    }
-  `
-  const actual = analyze(fixture).values.fontFamilies
-  const expected = {
-    total: 0,
-    totalUnique: 0,
-    unique: {},
-    uniquenessRatio: 0
-  }
-
-  assert.equal(actual, expected)
-})
-
-FontFamilies.run()
\ No newline at end of file
diff --git a/src/values/font-families.test.ts b/src/values/font-families.test.ts
new file mode 100644
index 00000000..c31555c7
--- /dev/null
+++ b/src/values/font-families.test.ts
@@ -0,0 +1,169 @@
+// oxlint-disable no-unused-expressions
+import { test } from 'vitest'
+import { expect } from 'vitest'
+import { analyze } from '../index.js'
+
+test('recognizes a font-family', () => {
+	const fixture = `
+    test {
+      font-family: "Droid Sans", serif;
+      font-family: sans-serif;
+      font-family: "Arial Black", 'Arial Bold', Gadget, sans-serif;
+      font-family: Brush Script MT, cursive;
+      font-family: monospace;
+      font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;
+      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
+
+      /* Unrelated */
+      color: brown;
+      font-size: 12px;
+    }
+  `
+	const actual = analyze(fixture).values.fontFamilies
+	const expected = {
+		total: 7,
+		totalUnique: 7,
+		unique: {
+			'"Droid Sans", serif': 1,
+			'sans-serif': 1,
+			[`"Arial Black", 'Arial Bold', Gadget, sans-serif`]: 1,
+			'Brush Script MT, cursive': 1,
+			monospace: 1,
+			'Consolas, "Liberation Mono", Menlo, Courier, monospace': 1,
+			'-apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"': 1,
+		},
+		uniquenessRatio: 7 / 7,
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('extracts the `font` shorthand', () => {
+	const fixture = `
+    test {
+      font: large 'Noto Sans';
+      font: normal normal 1em/1 "Source Sans Pro", serif;
+      font: normal normal 1.2em serif;
+      font: 400 1.3em/1 serif;
+      font: 1em / 1 serif;
+      font: 1em/ 1 serif;
+      font: 1em /1 serif;
+      font: normal normal 11px/1.5 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
+      font: 11px Consolas, "Liberation Mono", Menlo, Courier, monospace;
+      font: 0/0 a; /* As generated by some css minifiers */
+      font: 1.2em/1.2em; /* Found in indiatimes.com */
+      font: 12px var(--fontStack-monospace, ui-monospace, SFMono-Regular, SF Mono, Menlo, Consolas, Liberation Mono, monospace); /* From github.com */
+
+      /* Unrelated */
+      color: brown;
+      font-size: 123456789px;
+    }
+  `
+	const actual = analyze(fixture).values.fontFamilies
+	const expected = {
+		total: 12,
+		totalUnique: 8,
+		unique: {
+			[`'Noto Sans'`]: 1,
+			'"Source Sans Pro", serif': 1,
+			serif: 5,
+			'-apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"': 1,
+			'Consolas, "Liberation Mono", Menlo, Courier, monospace': 1,
+			a: 1,
+			'var(--fontStack-monospace, ui-monospace, SFMono-Regular, SF Mono, Menlo, Consolas, Liberation Mono, monospace)': 1,
+			// This entry exists due to a ??bug?? in CSSTree, but it's better than not counting the value above this as well
+			'ui-monospace, SFMono-Regular, SF Mono, Menlo, Consolas, Liberation Mono, monospace': 1,
+		},
+		uniquenessRatio: 8 / 12,
+	}
+	expect(actual).toEqual(expected)
+})
+
+test('does not crash on `12px var(...)', () => {
+	const fixture = `
+    test {
+      font: 12px var(--fontStack-monospace, ui-monospace, SFMono-Regular, SF Mono, Menlo, Consolas, Liberation Mono, monospace);
+    }
+  `
+	expect(() => {
+		analyze(fixture).values.fontFamilies
+	}).not.toThrow()
+})
+
+test('does not crash on 14px "Inter Var", sans-serif, 700', () => {
+	const fixture = `
+    test {
+      font: 14px "Inter Var", sans-serif, 700;
+    }
+  `
+	expect(() => {
+		analyze(fixture).values.fontFamilies
+	}).not.toThrow()
+	let { fontFamilies, fontSizes } = analyze(fixture).values
+	expect(fontFamilies.unique).toEqual({
+		'"Inter Var", sans-serif, 700': 1,
+	})
+	expect(fontSizes.unique).toEqual({
+		'14px': 1,
+	})
+})
+
+test('does not crash on var(--x, )', () => {
+	const fixture = `
+    a {
+      font: var(--x, );
+    }
+  `
+	expect(() => {
+		analyze(fixture).values.fontFamilies
+	}).not.toThrowError()
+})
+
+test('handles system fonts', () => {
+	// Source: https://drafts.csswg.org/css-fonts-3/#font-prop
+	const fixture = `
+    test {
+      font: menu;        /* use the font settings for system menus */
+      font: large menu;  /* use a font family named "menu" */
+    }
+  `
+	const actual = analyze(fixture).values.fontFamilies
+	const expected = {
+		total: 1,
+		totalUnique: 1,
+		unique: {
+			menu: 1,
+		},
+		uniquenessRatio: 1 / 1,
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('ignores keywords and global values', () => {
+	const fixture = `
+    test {
+      /* Global values */
+      font-family: inherit;
+      font-family: initial;
+      font-family: revert;
+      font-family: revert-layer;
+      font-family: unset;
+
+      font: inherit;
+      font: initial;
+      font: revert;
+      font: revert-layer;
+      font: unset;
+    }
+  `
+	const actual = analyze(fixture).values.fontFamilies
+	const expected = {
+		total: 0,
+		totalUnique: 0,
+		unique: {},
+		uniquenessRatio: 0,
+	}
+
+	expect(actual).toEqual(expected)
+})
diff --git a/src/values/font-sizes.test.js b/src/values/font-sizes.test.ts
similarity index 51%
rename from src/values/font-sizes.test.js
rename to src/values/font-sizes.test.ts
index 3ccf420e..05c45405 100644
--- a/src/values/font-sizes.test.js
+++ b/src/values/font-sizes.test.ts
@@ -1,11 +1,9 @@
-import { suite } from 'uvu';
-import * as assert from 'uvu/assert';
+import { test } from 'vitest'
+import { expect } from 'vitest'
 import { analyze } from '../index.js'
 
-const FontSizes = suite('FontSizes')
-
-FontSizes('recognizes a font-size', () => {
-  const fixture = `
+test('recognizes a font-size', () => {
+	const fixture = `
     test {
       font-size: 10px;
       font-size: small;
@@ -17,24 +15,24 @@ FontSizes('recognizes a font-size', () => {
       font-family: serif;
     }
   `
-  const actual = analyze(fixture).values.fontSizes
-  const expected = {
-    total: 4,
-    totalUnique: 4,
-    unique: {
-      '10px': 1,
-      'small': 1,
-      '1em': 1,
-      'calc(3vw + 1em)': 1,
-    },
-    uniquenessRatio: 4 / 4
-  }
+	const actual = analyze(fixture).values.fontSizes
+	const expected = {
+		total: 4,
+		totalUnique: 4,
+		unique: {
+			'10px': 1,
+			small: 1,
+			'1em': 1,
+			'calc(3vw + 1em)': 1,
+		},
+		uniquenessRatio: 4 / 4,
+	}
 
-  assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
-FontSizes('extracts the `font` shorthand', () => {
-  const fixture = `
+test('extracts the `font` shorthand', () => {
+	const fixture = `
     test {
       font: large "Noto Sans";
       font: normal normal 1em/1 "Source Sans Pro", serif;
@@ -55,49 +53,49 @@ FontSizes('extracts the `font` shorthand', () => {
       font-family: serif;
     }
   `
-  const actual = analyze(fixture).values.fontSizes
-  const expected = {
-    total: 13,
-    totalUnique: 9,
-    unique: {
-      '0': 1,
-      'large': 1,
-      '1em': 4,
-      '1.2em': 1,
-      '1.3em': 1,
-      '2em': 1,
-      '11px': 2,
-      '10PX': 1,
-      '12px': 1,
-    },
-    uniquenessRatio: 9 / 13
-  }
-  assert.equal(actual, expected)
+	const actual = analyze(fixture).values.fontSizes
+	const expected = {
+		total: 13,
+		totalUnique: 9,
+		unique: {
+			'0': 1,
+			large: 1,
+			'1em': 4,
+			'1.2em': 1,
+			'1.3em': 1,
+			'2em': 1,
+			'11px': 2,
+			'10PX': 1,
+			'12px': 1,
+		},
+		uniquenessRatio: 9 / 13,
+	}
+	expect(actual).toEqual(expected)
 })
 
-FontSizes('handles system fonts', () => {
-  // Source: https://drafts.csswg.org/css-fonts-3/#font-prop
-  const fixture = `
+test('handles system fonts', () => {
+	// Source: https://drafts.csswg.org/css-fonts-3/#font-prop
+	const fixture = `
     test {
       font: menu;        /* use the font settings for system menus */
       font: large menu;  /* use a font family named "menu" */
     }
   `
-  const actual = analyze(fixture).values.fontSizes
-  const expected = {
-    total: 1,
-    totalUnique: 1,
-    unique: {
-      'large': 1,
-    },
-    uniquenessRatio: 1
-  }
+	const actual = analyze(fixture).values.fontSizes
+	const expected = {
+		total: 1,
+		totalUnique: 1,
+		unique: {
+			large: 1,
+		},
+		uniquenessRatio: 1,
+	}
 
-  assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
-FontSizes('ignores keywords and global values', () => {
-  const fixture = `
+test('ignores keywords and global values', () => {
+	const fixture = `
     test {
       /* Global values */
       font-size: inherit;
@@ -113,15 +111,13 @@ FontSizes('ignores keywords and global values', () => {
       font: unset;
     }
   `
-  const actual = analyze(fixture).values.fontSizes
-  const expected = {
-    total: 0,
-    totalUnique: 0,
-    unique: {},
-    uniquenessRatio: 0
-  }
+	const actual = analyze(fixture).values.fontSizes
+	const expected = {
+		total: 0,
+		totalUnique: 0,
+		unique: {},
+		uniquenessRatio: 0,
+	}
 
-  assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
-
-FontSizes.run()
\ No newline at end of file
diff --git a/src/values/gradients.test.js b/src/values/gradients.test.ts
similarity index 91%
rename from src/values/gradients.test.js
rename to src/values/gradients.test.ts
index 1d445a75..6ce563b0 100644
--- a/src/values/gradients.test.js
+++ b/src/values/gradients.test.ts
@@ -1,10 +1,8 @@
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
+import { test } from 'vitest'
+import { expect } from 'vitest'
 import { analyze } from '../index.js'
 
-const Gradients = suite('Gradients')
-
-Gradients('finds linear-gradient', () => {
+test('finds linear-gradient', () => {
 	const fixture = `
     gradient {
       background-image: -webkit-linear-gradient(to right,#00f 10%,rgba(51,51,255,0) 42%);
@@ -33,13 +31,13 @@ Gradients('finds linear-gradient', () => {
 			'-webkit-gradient(linear,left top,right top,color-stop(50%,#ccc),color-stop(50%,#fff))': 1,
 		},
 		totalUnique: 9,
-		uniquenessRatio: 1
+		uniquenessRatio: 1,
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
-Gradients('finds repeating-linear-gradient', () => {
+test('finds repeating-linear-gradient', () => {
 	const fixture = `
     gradient {
       background-image: repeating-linear-gradient(45deg,transparent,transparent 8px,rgba(0,0,0,.03) 8px,rgba(0,0,0,.03) 10px);
@@ -99,10 +97,10 @@ Gradients('finds repeating-linear-gradient', () => {
 		uniquenessRatio: 1,
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
-Gradients('finds radial gradient', () => {
+test('finds radial gradient', () => {
 	const fixture = `
     radial {
       background-image: -webkit-radial-gradient(0% 100%,circle farthest-corner,rgba(255,255,255,.8) 40%,#e5f4e9 0);
@@ -123,13 +121,13 @@ Gradients('finds radial gradient', () => {
 			'radial-gradient(85.37% 69.72% at 50% 12.59%, rgba(255, 0, 0, 0.8) 3.14%, rgba(178, 1, 1, 0.8) 62.94%, rgba(47, 3, 3, 0.424) 100%)': 1,
 		},
 		totalUnique: 5,
-		uniquenessRatio: 1
+		uniquenessRatio: 1,
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
-Gradients('finds repeating-radial-gradient', () => {
+test('finds repeating-radial-gradient', () => {
 	const fixture = `
     gradient {
       background: repeating-radial-gradient(
@@ -179,13 +177,13 @@ Gradients('finds repeating-radial-gradient', () => {
 			[z]: 1,
 		},
 		totalUnique: 3,
-		uniquenessRatio: 1
+		uniquenessRatio: 1,
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
-Gradients('finds conic gradient', () => {
+test('finds conic gradient', () => {
 	const fixture = `
     conic {
       /* A conic gradient rotated 45 degrees,
@@ -231,13 +229,13 @@ Gradients('finds conic gradient', () => {
 			[wheel]: 1,
 		},
 		totalUnique: 3,
-		uniquenessRatio: 1
+		uniquenessRatio: 1,
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
-Gradients('finds repeating-conic-gradient', () => {
+test('finds repeating-conic-gradient', () => {
 	const fixture = `
     gradient {
 			background: repeating-conic-gradient(
@@ -271,13 +269,13 @@ Gradients('finds repeating-conic-gradient', () => {
 			'repeating-conic-gradient(from -45deg, red 45deg, orange, yellow, green, blue 225deg)': 1,
 		},
 		totalUnique: 4,
-		uniquenessRatio: 1
+		uniquenessRatio: 1,
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
-Gradients('ignores keywords', () => {
+test('ignores keywords', () => {
 	const fixture = `
     keywords {
       background-image: none;
@@ -295,10 +293,8 @@ Gradients('ignores keywords', () => {
 		total: 0,
 		unique: {},
 		totalUnique: 0,
-		uniquenessRatio: 0
+		uniquenessRatio: 0,
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
-
-Gradients.run()
\ No newline at end of file
diff --git a/src/values/keywords.test.js b/src/values/keywords.test.ts
similarity index 79%
rename from src/values/keywords.test.js
rename to src/values/keywords.test.ts
index a0a8109a..ca7e148a 100644
--- a/src/values/keywords.test.js
+++ b/src/values/keywords.test.ts
@@ -1,9 +1,7 @@
-import { suite } from 'uvu';
-import * as assert from 'uvu/assert';
+import { test } from 'vitest'
+import { expect } from 'vitest'
 import { analyze } from '../index.js'
 
-const test = suite('Global Keywords')
-
 test('finds global keywords', () => {
 	const fixture = `
 		test {
@@ -30,12 +28,12 @@ test('finds global keywords', () => {
 			initial: 2,
 			revert: 2,
 			'revert-layer': 2,
-			unset: 2
+			unset: 2,
 		},
-		uniquenessRatio: 5 / 10
+		uniquenessRatio: 5 / 10,
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
 test('finds global keywords in shorthands', () => {
@@ -52,12 +50,12 @@ test('finds global keywords in shorthands', () => {
 		totalUnique: 2,
 		unique: {
 			inherit: 2,
-			auto: 1
+			auto: 1,
 		},
-		uniquenessRatio: 2 / 3
+		uniquenessRatio: 2 / 3,
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
 test('finds global keywords in multi-values', () => {
@@ -75,10 +73,8 @@ test('finds global keywords in multi-values', () => {
 			auto: 1,
 			inherit: 2,
 		},
-		uniquenessRatio: 2 / 3
+		uniquenessRatio: 2 / 3,
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
-
-test.run()
diff --git a/src/values/line-heights.test.js b/src/values/line-heights.test.ts
similarity index 78%
rename from src/values/line-heights.test.js
rename to src/values/line-heights.test.ts
index 8e3adb7a..4f2f63bc 100644
--- a/src/values/line-heights.test.js
+++ b/src/values/line-heights.test.ts
@@ -1,10 +1,8 @@
-import { suite } from 'uvu';
-import * as assert from 'uvu/assert';
+import { test } from 'vitest'
+import { expect } from 'vitest'
 import { analyze } from '../index.js'
 
-const LineHeights = suite('LineHeights')
-
-LineHeights('recognizes line-height', () => {
+test('recognizes line-height', () => {
 	const fixture = `
     test {
       line-height: 1;
@@ -26,15 +24,15 @@ LineHeights('recognizes line-height', () => {
 			'100%': 1,
 			'calc(1em + 2vh)': 1,
 			'2em': 1,
-			'normal': 1,
+			normal: 1,
 		},
-		uniquenessRatio: 5 / 5
+		uniquenessRatio: 5 / 5,
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
-LineHeights('extracts the `font` shorthand', () => {
+test('extracts the `font` shorthand', () => {
 	const fixture = `
     test {
       font: large 'Noto Sans';
@@ -61,12 +59,12 @@ LineHeights('extracts the `font` shorthand', () => {
 			'1.5': 1,
 			'0': 1,
 		},
-		uniquenessRatio: 3 / 7
+		uniquenessRatio: 3 / 7,
 	}
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
-LineHeights('handles system fonts', () => {
+test('handles system fonts', () => {
 	// Source: https://drafts.csswg.org/css-fonts-3/#font-prop
 	const fixture = `
     test {
@@ -79,13 +77,13 @@ LineHeights('handles system fonts', () => {
 		total: 0,
 		totalUnique: 0,
 		unique: {},
-		uniquenessRatio: 0
+		uniquenessRatio: 0,
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
 
-LineHeights('ignores keywords and global values', () => {
+test('ignores keywords and global values', () => {
 	const fixture = `
 		test {
 			/* Global values */
@@ -107,10 +105,8 @@ LineHeights('ignores keywords and global values', () => {
 		total: 0,
 		totalUnique: 0,
 		unique: {},
-		uniquenessRatio: 0
+		uniquenessRatio: 0,
 	}
 
-	assert.equal(actual, expected)
+	expect(actual).toEqual(expected)
 })
-
-LineHeights.run()
diff --git a/src/values/resets.test.js b/src/values/resets.test.ts
similarity index 69%
rename from src/values/resets.test.js
rename to src/values/resets.test.ts
index 82f8946c..d5c7e140 100644
--- a/src/values/resets.test.js
+++ b/src/values/resets.test.ts
@@ -1,8 +1,6 @@
-import { analyze } from "../index.js"
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
-
-const test = suite("resets")
+import { analyze } from '../index.js'
+import { test } from 'vitest'
+import { expect } from 'vitest'
 
 test('does not report false positives', () => {
 	let actual = analyze(`t {
@@ -12,8 +10,8 @@ test('does not report false positives', () => {
 		margin: 10px auto;
 	}`)
 	let resets = actual.values.resets
-	assert.is(resets.total, 0)
-	assert.equal(resets.unique, {})
+	expect(resets.total).toBe(0)
+	expect(resets.unique).toEqual({})
 })
 
 test('accepts zeroes with units', () => {
@@ -22,7 +20,7 @@ test('accepts zeroes with units', () => {
 		padding: 0px 0dvh 0rem 0in;
 	}`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'margin': 1, 'padding': 1 })
+	expect(resets.unique).toEqual({ margin: 1, padding: 1 })
 })
 
 test('crazy notations', () => {
@@ -41,7 +39,7 @@ test('crazy notations', () => {
 		margin: +0.0e0;
 	}`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'margin': 12 })
+	expect(resets.unique).toEqual({ margin: 12 })
 })
 
 test('accepts weird casing', () => {
@@ -49,7 +47,7 @@ test('accepts weird casing', () => {
 		MARGIN: 0;
 	}`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'MARGIN': 1 })
+	expect(resets.unique).toEqual({ MARGIN: 1 })
 })
 
 test('accepts vendor prefixes', () => {
@@ -57,7 +55,7 @@ test('accepts vendor prefixes', () => {
 		-webkit-margin: 0;
 	}`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { '-webkit-margin': 1 })
+	expect(resets.unique).toEqual({ '-webkit-margin': 1 })
 })
 
 // Test all properties
@@ -65,85 +63,85 @@ test('accepts vendor prefixes', () => {
 test('margin: 0', () => {
 	let actual = analyze(`t { margin: 0; }`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'margin': 1 })
+	expect(resets.unique).toEqual({ margin: 1 })
 })
 
 test('margin-top: 0', () => {
 	let actual = analyze(`t { margin-top: 0; }`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'margin-top': 1 })
+	expect(resets.unique).toEqual({ 'margin-top': 1 })
 })
 
 test('margin-right: 0', () => {
 	let actual = analyze(`t { margin-right: 0; }`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'margin-right': 1 })
+	expect(resets.unique).toEqual({ 'margin-right': 1 })
 })
 
 test('margin-bottom: 0', () => {
 	let actual = analyze(`t { margin-bottom: 0; }`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'margin-bottom': 1 })
+	expect(resets.unique).toEqual({ 'margin-bottom': 1 })
 })
 
 test('margin-left: 0', () => {
 	let actual = analyze(`t { margin-left: 0; }`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'margin-left': 1 })
+	expect(resets.unique).toEqual({ 'margin-left': 1 })
 })
 
 test('margin-inline: 0', () => {
 	let actual = analyze(`t { margin-inline: 0; }`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'margin-inline': 1 })
+	expect(resets.unique).toEqual({ 'margin-inline': 1 })
 })
 
 test('margin-block: 0', () => {
 	let actual = analyze(`t { margin-block: 0; }`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'margin-block': 1 })
+	expect(resets.unique).toEqual({ 'margin-block': 1 })
 })
 
 test('padding: 0', () => {
 	let actual = analyze(`t { padding: 0; }`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'padding': 1 })
+	expect(resets.unique).toEqual({ padding: 1 })
 })
 
 test('padding-top: 0', () => {
 	let actual = analyze(`t { padding-top: 0; }`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'padding-top': 1 })
+	expect(resets.unique).toEqual({ 'padding-top': 1 })
 })
 
 test('padding-right: 0', () => {
 	let actual = analyze(`t { padding-right: 0; }`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'padding-right': 1 })
+	expect(resets.unique).toEqual({ 'padding-right': 1 })
 })
 
 test('padding-bottom: 0', () => {
 	let actual = analyze(`t { padding-bottom: 0; }`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'padding-bottom': 1 })
+	expect(resets.unique).toEqual({ 'padding-bottom': 1 })
 })
 
 test('padding-left: 0', () => {
 	let actual = analyze(`t { padding-left: 0; }`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'padding-left': 1 })
+	expect(resets.unique).toEqual({ 'padding-left': 1 })
 })
 
 test('padding-inline: 0', () => {
 	let actual = analyze(`t { padding-inline: 0; }`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'padding-inline': 1 })
+	expect(resets.unique).toEqual({ 'padding-inline': 1 })
 })
 
 test('padding-block: 0', () => {
 	let actual = analyze(`t { padding-block: 0; }`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'padding-block': 1 })
+	expect(resets.unique).toEqual({ 'padding-block': 1 })
 })
 
 // Shorthands
@@ -151,25 +149,23 @@ test('padding-block: 0', () => {
 test('margin-inline: 0 0', () => {
 	let actual = analyze(`t { margin-inline: 0 0; }`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'margin-inline': 1 })
+	expect(resets.unique).toEqual({ 'margin-inline': 1 })
 })
 
 test('padding-inline: 0 0', () => {
 	let actual = analyze(`t { padding-inline: 0 0; }`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'padding-inline': 1 })
+	expect(resets.unique).toEqual({ 'padding-inline': 1 })
 })
 
 test('margin-block: 0 0', () => {
 	let actual = analyze(`t { margin-block: 0 0; }`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'margin-block': 1 })
+	expect(resets.unique).toEqual({ 'margin-block': 1 })
 })
 
 test('padding-block: 0 0', () => {
 	let actual = analyze(`t { padding-block: 0 0; }`)
 	let resets = actual.values.resets
-	assert.equal(resets.unique, { 'padding-block': 1 })
+	expect(resets.unique).toEqual({ 'padding-block': 1 })
 })
-
-test.run()
diff --git a/src/values/text-shadows.test.js b/src/values/text-shadows.test.js
deleted file mode 100644
index 5f7d0fa8..00000000
--- a/src/values/text-shadows.test.js
+++ /dev/null
@@ -1,98 +0,0 @@
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
-import { analyze } from '../index.js'
-
-const TextShadows = suite('TextShadows')
-
-TextShadows('finds simple values', () => {
-  const fixture = `
-    text-shadows-simple {
-      text-shadow: 1px 1px 2px black;
-      text-shadow: #fc0 1px 0 10px;
-      text-shadow: 5px 5px #558abb;
-      text-shadow: white 2px 5px;
-      text-shadow: 5px 10px;
-      text-shadow: red 0 -2px;
-    }
-  `
-  const actual = analyze(fixture).values.textShadows
-  const expected = {
-    total: 6,
-    unique: {
-      '1px 1px 2px black': 1,
-      '#fc0 1px 0 10px': 1,
-      '5px 5px #558abb': 1,
-      'white 2px 5px': 1,
-      '5px 10px': 1,
-      'red 0 -2px': 1,
-    },
-    totalUnique: 6,
-    uniquenessRatio: 1
-  }
-
-  assert.equal(actual, expected)
-})
-
-TextShadows('finds complex values', () => {
-  const fixture = `
-    text-shadows-complex {
-      text-shadow: 1px 1px 2px black, 0 0 1em blue, 0 0 0.2em blue;
-    }
-  `
-  const actual = analyze(fixture).values.textShadows
-  const expected = {
-    total: 1,
-    unique: {
-      '1px 1px 2px black, 0 0 1em blue, 0 0 0.2em blue': 1,
-    },
-    totalUnique: 1,
-    uniquenessRatio: 1
-  }
-
-  assert.equal(actual, expected)
-})
-
-TextShadows('finds vendor prefixed values', () => {
-  const fixture = `
-    text-shadows-vendor-prefixed {
-      -webkit-text-shadow: 1px 1px 2px black;
-    }
-  `
-  const actual = analyze(fixture).values.textShadows
-  const expected = {
-    total: 1,
-    unique: {
-      '1px 1px 2px black': 1,
-    },
-    totalUnique: 1,
-    uniquenessRatio: 1
-  }
-
-  assert.equal(actual, expected)
-})
-
-TextShadows('ignores keywords', () => {
-  const fixture = `
-    text-shadows-keyword {
-      text-shadow: none;
-
-      /* Global values */
-      text-shadow: inherit;
-      text-shadow: initial;
-      text-shadow: revert;
-      text-shadow: revert-layer;
-      text-shadow: unset;
-    }
-  `
-  const actual = analyze(fixture).values.textShadows
-  const expected = {
-    total: 0,
-    unique: {},
-    totalUnique: 0,
-    uniquenessRatio: 0
-  }
-
-  assert.equal(actual, expected)
-})
-
-TextShadows.run()
\ No newline at end of file
diff --git a/src/values/text-shadows.test.ts b/src/values/text-shadows.test.ts
new file mode 100644
index 00000000..2f84de96
--- /dev/null
+++ b/src/values/text-shadows.test.ts
@@ -0,0 +1,94 @@
+import { test } from 'vitest'
+import { expect } from 'vitest'
+import { analyze } from '../index.js'
+
+test('finds simple values', () => {
+	const fixture = `
+    text-shadows-simple {
+      text-shadow: 1px 1px 2px black;
+      text-shadow: #fc0 1px 0 10px;
+      text-shadow: 5px 5px #558abb;
+      text-shadow: white 2px 5px;
+      text-shadow: 5px 10px;
+      text-shadow: red 0 -2px;
+    }
+  `
+	const actual = analyze(fixture).values.textShadows
+	const expected = {
+		total: 6,
+		unique: {
+			'1px 1px 2px black': 1,
+			'#fc0 1px 0 10px': 1,
+			'5px 5px #558abb': 1,
+			'white 2px 5px': 1,
+			'5px 10px': 1,
+			'red 0 -2px': 1,
+		},
+		totalUnique: 6,
+		uniquenessRatio: 1,
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('finds complex values', () => {
+	const fixture = `
+    text-shadows-complex {
+      text-shadow: 1px 1px 2px black, 0 0 1em blue, 0 0 0.2em blue;
+    }
+  `
+	const actual = analyze(fixture).values.textShadows
+	const expected = {
+		total: 1,
+		unique: {
+			'1px 1px 2px black, 0 0 1em blue, 0 0 0.2em blue': 1,
+		},
+		totalUnique: 1,
+		uniquenessRatio: 1,
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('finds vendor prefixed values', () => {
+	const fixture = `
+    text-shadows-vendor-prefixed {
+      -webkit-text-shadow: 1px 1px 2px black;
+    }
+  `
+	const actual = analyze(fixture).values.textShadows
+	const expected = {
+		total: 1,
+		unique: {
+			'1px 1px 2px black': 1,
+		},
+		totalUnique: 1,
+		uniquenessRatio: 1,
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('ignores keywords', () => {
+	const fixture = `
+    text-shadows-keyword {
+      text-shadow: none;
+
+      /* Global values */
+      text-shadow: inherit;
+      text-shadow: initial;
+      text-shadow: revert;
+      text-shadow: revert-layer;
+      text-shadow: unset;
+    }
+  `
+	const actual = analyze(fixture).values.textShadows
+	const expected = {
+		total: 0,
+		unique: {},
+		totalUnique: 0,
+		uniquenessRatio: 0,
+	}
+
+	expect(actual).toEqual(expected)
+})
diff --git a/src/values/units.test.js b/src/values/units.test.js
deleted file mode 100644
index e5ff56ae..00000000
--- a/src/values/units.test.js
+++ /dev/null
@@ -1,88 +0,0 @@
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
-import { analyze } from '../index.js'
-
-const Units = suite('Units')
-
-Units('analyzes length units', () => {
-  const fixture = `
-    test {
-      font: normal 10px/11px Arial;
-      font: 14px sans-serif;
-    }
-
-    @media (min-width: 10em) {
-      test2 {
-        width: 12vw;
-        height: 13vmin;
-      }
-    }
-
-    @supports (hover: hover) {
-      @media all {
-        @media screen and (max-width: 100px) {
-          line-height: 2;
-        }
-      }
-    }
-  `
-  const result = analyze(fixture)
-  const actual = result.values.units
-
-  const expected = {
-    total: 5,
-    totalUnique: 3,
-    uniquenessRatio: 3 / 5,
-    unique: {
-      px: 3,
-      vw: 1,
-      vmin: 1,
-    },
-    itemsPerContext: {
-      font: {
-        total: 3,
-        totalUnique: 1,
-        uniquenessRatio: 1 / 3,
-        unique: {
-          px: 3,
-        },
-      },
-      width: {
-        total: 1,
-        totalUnique: 1,
-        uniquenessRatio: 1,
-        unique: {
-          vw: 1,
-        },
-      },
-      height: {
-        total: 1,
-        totalUnique: 1,
-        uniquenessRatio: 1,
-        unique: {
-          vmin: 1,
-        },
-      },
-    },
-  }
-
-  assert.equal(actual, expected)
-})
-
-Units('should not include browserhacks', () => {
-  let actual = analyze(`
-    a {
-      font-size: 10px\\9;
-      color: 1em!ie;
-    }
-  `).values.units;
-
-  assert.equal(actual.unique, {
-    'px': 1,
-    'em': 1,
-  })
-  assert.is(actual.total, 2)
-  assert.is(actual.totalUnique, 2)
-})
-
-Units.run()
\ No newline at end of file
diff --git a/src/values/units.test.ts b/src/values/units.test.ts
new file mode 100644
index 00000000..7fc5ff54
--- /dev/null
+++ b/src/values/units.test.ts
@@ -0,0 +1,84 @@
+import { test } from 'vitest'
+import { expect } from 'vitest'
+import { analyze } from '../index.js'
+
+test('analyzes length units', () => {
+	const fixture = `
+    test {
+      font: normal 10px/11px Arial;
+      font: 14px sans-serif;
+    }
+
+    @media (min-width: 10em) {
+      test2 {
+        width: 12vw;
+        height: 13vmin;
+      }
+    }
+
+    @supports (hover: hover) {
+      @media all {
+        @media screen and (max-width: 100px) {
+          line-height: 2;
+        }
+      }
+    }
+  `
+	const result = analyze(fixture)
+	const actual = result.values.units
+
+	const expected = {
+		total: 5,
+		totalUnique: 3,
+		uniquenessRatio: 3 / 5,
+		unique: {
+			px: 3,
+			vw: 1,
+			vmin: 1,
+		},
+		itemsPerContext: {
+			font: {
+				total: 3,
+				totalUnique: 1,
+				uniquenessRatio: 1 / 3,
+				unique: {
+					px: 3,
+				},
+			},
+			width: {
+				total: 1,
+				totalUnique: 1,
+				uniquenessRatio: 1,
+				unique: {
+					vw: 1,
+				},
+			},
+			height: {
+				total: 1,
+				totalUnique: 1,
+				uniquenessRatio: 1,
+				unique: {
+					vmin: 1,
+				},
+			},
+		},
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('should not include browserhacks', () => {
+	let actual = analyze(`
+    a {
+      font-size: 10px\\9;
+      color: 1em!ie;
+    }
+  `).values.units
+
+	expect(actual.unique).toEqual({
+		px: 1,
+		em: 1,
+	})
+	expect(actual.total).toBe(2)
+	expect(actual.totalUnique).toBe(2)
+})
diff --git a/src/values/values.js b/src/values/values.js
deleted file mode 100644
index 6a662c34..00000000
--- a/src/values/values.js
+++ /dev/null
@@ -1,48 +0,0 @@
-import { KeywordSet } from "../keyword-set.js"
-import { Identifier, Value, Nr, Dimension } from "../css-tree-node-types.js"
-
-export const keywords = new KeywordSet([
-  'auto',
-  'none', // for `text-shadow`, `box-shadow` and `background`
-  'inherit',
-  'initial',
-  'unset',
-  'revert',
-  'revert-layer',
-])
-
-/**
- * @param {import('css-tree').Value} node
- */
-export function isValueKeyword(node) {
-  let children = node.children
-  let size = children.size
-
-  if (!children) return false
-  if (size > 1 || size === 0) return false
-
-  let firstChild = children.first
-  return firstChild.type === Identifier && keywords.has(firstChild.name)
-}
-
-/**
- * @param {string} string
- * @returns {boolean}
- */
-function isZero(string) {
-  return parseFloat(string) === 0
-}
-
-/**
- * Test whether a value is a reset (0, 0px, -0.0e0 etc.)
- * @param {import('css-tree').Value} node
- */
-export function isValueReset(node) {
-  for (let child of node.children.toArray()) {
-    if (child.type === Nr && isZero(child.value)) continue
-    if (child.type === Dimension && isZero(child.value)) continue
-    return false
-  }
-
-  return true
-}
diff --git a/src/values/values.ts b/src/values/values.ts
new file mode 100644
index 00000000..cea6a572
--- /dev/null
+++ b/src/values/values.ts
@@ -0,0 +1,41 @@
+import { KeywordSet } from '../keyword-set.js'
+import { Identifier, Nr, Dimension } from '../css-tree-node-types.js'
+import type { Value } from 'css-tree'
+
+export const keywords = new KeywordSet([
+	'auto',
+	'none', // for `text-shadow`, `box-shadow` and `background`
+	'inherit',
+	'initial',
+	'unset',
+	'revert',
+	'revert-layer',
+])
+
+export function isValueKeyword(node: Value) {
+	let children = node.children
+	let size = children.size
+
+	if (!children) return false
+	if (size > 1 || size === 0) return false
+
+	let firstChild = children.first
+	return firstChild!.type === Identifier && keywords.has(firstChild.name)
+}
+
+function isZero(string: string): boolean {
+	return parseFloat(string) === 0
+}
+
+/**
+ * Test whether a value is a reset (0, 0px, -0.0e0 etc.)
+ */
+export function isValueReset(node: Value): boolean {
+	for (let child of node.children.toArray()) {
+		if (child.type === Nr && isZero(child.value)) continue
+		if (child.type === Dimension && isZero(child.value)) continue
+		return false
+	}
+
+	return true
+}
diff --git a/src/values/vendor-prefix.js b/src/values/vendor-prefix.js
deleted file mode 100644
index 0a127c41..00000000
--- a/src/values/vendor-prefix.js
+++ /dev/null
@@ -1,29 +0,0 @@
-import { hasVendorPrefix } from '../vendor-prefix.js'
-import { Func, Identifier } from '../css-tree-node-types.js'
-
-/**
- * @param {import('css-tree').Value} node
- */
-export function isValuePrefixed(node) {
-  let children = node.children
-
-  if (!children) {
-    return false
-  }
-
-  for (let node of children) {
-    let { type, name } = node;
-
-    if (type === Identifier && hasVendorPrefix(name)) {
-      return true
-    }
-
-    if (type === Func) {
-      if (hasVendorPrefix(name) || isValuePrefixed(node)) {
-        return true
-      }
-    }
-  }
-
-  return false
-}
diff --git a/src/values/vendor-prefix.test.js b/src/values/vendor-prefix.test.js
deleted file mode 100644
index 7d2adf56..00000000
--- a/src/values/vendor-prefix.test.js
+++ /dev/null
@@ -1,98 +0,0 @@
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
-import { analyze } from '../index.js'
-
-const VendorPrefix = suite('VendorPrefixedValue')
-
-VendorPrefix('finds simple prefixes', () => {
-  const fixture = `
-    value-vendor-prefix-simple {
-      width: -moz-max-content;
-      width: -webkit-max-content;
-      box-shadow: 0 0 0 3px -moz-mac-focusring;
-      position: -webkit-sticky;
-      -webkit-transition: -webkit-transform 0.3s ease-out;
-      -moz-transition: -moz-transform 0.3s ease-out;
-      -o-transition: -o-transform 0.3s ease-out;
-      transition: -o-transform 0.3s ease-out;
-    }
-
-    not-a-prefix {
-      background: var(--test);
-      margin: -0.3em;
-    }
-
-    @supports (position: -webkit-sticky) {
-      thing {
-        position: -webkit-sticky;
-        position: sticky;
-      }
-    }
-  `
-  const actual = analyze(fixture).values.prefixes
-  const expected = {
-    total: 9,
-    totalUnique: 7,
-    unique: {
-      '-moz-max-content': 1,
-      '-webkit-max-content': 1,
-      '0 0 0 3px -moz-mac-focusring': 1,
-      '-webkit-sticky': 2,
-      '-webkit-transform 0.3s ease-out': 1,
-      '-moz-transform 0.3s ease-out': 1,
-      '-o-transform 0.3s ease-out': 2,
-    },
-    uniquenessRatio: 7 / 9,
-  }
-
-  assert.equal(actual, expected)
-})
-
-VendorPrefix('finds nested prefixes', () => {
-  const fixture = `
-    value-vendor-prefix-nested {
-      background-image: -khtml-linear-gradient(90deg, red, green);
-      background:
-        red,
-        -webkit-linear-gradient(transparent, transparent),
-        -moz-linear-gradient(transparent, transparent),
-        -ms-linear-gradient(transparent, transparent),
-        -o-linear-gradient(transparent, transparent);
-      grid-template-columns: repeat(3, max(-webkit-max-content, 100vw));
-    }
-  `
-  const actual = analyze(fixture).values.prefixes
-  const expected = {
-    total: 3,
-    totalUnique: 3,
-    unique: {
-      '-khtml-linear-gradient(90deg, red, green)': 1,
-      'red,\n        -webkit-linear-gradient(transparent, transparent),\n        -moz-linear-gradient(transparent, transparent),\n        -ms-linear-gradient(transparent, transparent),\n        -o-linear-gradient(transparent, transparent)': 1,
-      'repeat(3, max(-webkit-max-content, 100vw))': 1,
-    },
-    uniquenessRatio: 1
-  }
-
-  assert.equal(actual, expected)
-})
-
-VendorPrefix.skip('finds DEEPLY nested prefixes', () => {
-  const fixture = `
-    value-vendor-prefix-deeply-nested {
-      width: var(--test, -webkit-max-content);
-    }
-  `
-  const actual = analyze(fixture).values.prefixes
-  const expected = {
-    total: 1,
-    totalUnique: 1,
-    unique: {
-      'var(--test, -webkit-max-content)': 1,
-    },
-    uniquenessRatio: 1
-  }
-
-  assert.equal(actual, expected)
-})
-
-VendorPrefix.run()
\ No newline at end of file
diff --git a/src/values/vendor-prefix.test.ts b/src/values/vendor-prefix.test.ts
new file mode 100644
index 00000000..758970af
--- /dev/null
+++ b/src/values/vendor-prefix.test.ts
@@ -0,0 +1,94 @@
+import { test } from 'vitest'
+import { expect } from 'vitest'
+import { analyze } from '../index.js'
+
+test('finds simple prefixes', () => {
+	const fixture = `
+    value-vendor-prefix-simple {
+      width: -moz-max-content;
+      width: -webkit-max-content;
+      box-shadow: 0 0 0 3px -moz-mac-focusring;
+      position: -webkit-sticky;
+      -webkit-transition: -webkit-transform 0.3s ease-out;
+      -moz-transition: -moz-transform 0.3s ease-out;
+      -o-transition: -o-transform 0.3s ease-out;
+      transition: -o-transform 0.3s ease-out;
+    }
+
+    not-a-prefix {
+      background: var(--test);
+      margin: -0.3em;
+    }
+
+    @supports (position: -webkit-sticky) {
+      thing {
+        position: -webkit-sticky;
+        position: sticky;
+      }
+    }
+  `
+	const actual = analyze(fixture).values.prefixes
+	const expected = {
+		total: 9,
+		totalUnique: 7,
+		unique: {
+			'-moz-max-content': 1,
+			'-webkit-max-content': 1,
+			'0 0 0 3px -moz-mac-focusring': 1,
+			'-webkit-sticky': 2,
+			'-webkit-transform 0.3s ease-out': 1,
+			'-moz-transform 0.3s ease-out': 1,
+			'-o-transform 0.3s ease-out': 2,
+		},
+		uniquenessRatio: 7 / 9,
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('finds nested prefixes', () => {
+	const fixture = `
+    value-vendor-prefix-nested {
+      background-image: -khtml-linear-gradient(90deg, red, green);
+      background:
+        red,
+        -webkit-linear-gradient(transparent, transparent),
+        -moz-linear-gradient(transparent, transparent),
+        -ms-linear-gradient(transparent, transparent),
+        -o-linear-gradient(transparent, transparent);
+      grid-template-columns: repeat(3, max(-webkit-max-content, 100vw));
+    }
+  `
+	const actual = analyze(fixture).values.prefixes
+	const expected = {
+		total: 3,
+		totalUnique: 3,
+		unique: {
+			'-khtml-linear-gradient(90deg, red, green)': 1,
+			'red,\n        -webkit-linear-gradient(transparent, transparent),\n        -moz-linear-gradient(transparent, transparent),\n        -ms-linear-gradient(transparent, transparent),\n        -o-linear-gradient(transparent, transparent)': 1,
+			'repeat(3, max(-webkit-max-content, 100vw))': 1,
+		},
+		uniquenessRatio: 1,
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test.skip('finds DEEPLY nested prefixes', () => {
+	const fixture = `
+    value-vendor-prefix-deeply-nested {
+      width: var(--test, -webkit-max-content);
+    }
+  `
+	const actual = analyze(fixture).values.prefixes
+	const expected = {
+		total: 1,
+		totalUnique: 1,
+		unique: {
+			'var(--test, -webkit-max-content)': 1,
+		},
+		uniquenessRatio: 1,
+	}
+
+	expect(actual).toEqual(expected)
+})
diff --git a/src/values/vendor-prefix.ts b/src/values/vendor-prefix.ts
new file mode 100644
index 00000000..6c981cf9
--- /dev/null
+++ b/src/values/vendor-prefix.ts
@@ -0,0 +1,28 @@
+import { hasVendorPrefix } from '../vendor-prefix.js'
+import { Func, Identifier } from '../css-tree-node-types.js'
+import type { CssNode, Value } from 'css-tree'
+
+export function isValuePrefixed(node: Value | CssNode): boolean {
+	// @ts-expect-error TODO: fix this
+	let children = node.children
+
+	if (!children) {
+		return false
+	}
+
+	for (let node of children) {
+		let { type, name } = node
+
+		if (type === Identifier && hasVendorPrefix(name)) {
+			return true
+		}
+
+		if (type === Func) {
+			if (hasVendorPrefix(name) || isValuePrefixed(node)) {
+				return true
+			}
+		}
+	}
+
+	return false
+}
diff --git a/src/values/z-index.test.js b/src/values/z-index.test.js
deleted file mode 100644
index 39944120..00000000
--- a/src/values/z-index.test.js
+++ /dev/null
@@ -1,62 +0,0 @@
-import { suite } from 'uvu'
-import * as assert from 'uvu/assert'
-import { analyze } from '../index.js'
-
-const ZIndex = suite('Z-index')
-
-ZIndex('finds simple values', () => {
-  const fixture = `
-    test {
-      z-index: 1;
-      z-index: 0;
-      z-index: -1;
-      z-index: 99999;
-      z-index: -100;
-      z-index: 0;
-      z-index: auto;
-      z-index: calc(var(--model-z-index) - 1);
-    }
-  `
-  const actual = analyze(fixture).values.zindexes
-  const expected = {
-    total: 7,
-    totalUnique: 6,
-    unique: {
-      '0': 2,
-      '1': 1,
-      '99999': 1,
-      '-1': 1,
-      '-100': 1,
-      'calc(var(--model-z-index) - 1)': 1,
-    },
-    uniquenessRatio: 6 / 7
-  }
-
-  assert.equal(actual, expected)
-})
-
-ZIndex('ignores global CSS keywords', () => {
-  const fixture = `
-    test {
-      z-index: auto;
-
-      /* Global values */
-      z-index: inherit;
-      z-index: initial;
-      z-index: revert;
-      z-index: revert-layer;
-      z-index: unset;
-    }
-  `
-  const actual = analyze(fixture).values.zindexes
-  const expected = {
-    total: 0,
-    totalUnique: 0,
-    unique: {},
-    uniquenessRatio: 0
-  }
-
-  assert.equal(actual, expected)
-})
-
-ZIndex.run()
\ No newline at end of file
diff --git a/src/values/z-index.test.ts b/src/values/z-index.test.ts
new file mode 100644
index 00000000..5d13be4e
--- /dev/null
+++ b/src/values/z-index.test.ts
@@ -0,0 +1,58 @@
+import { test } from 'vitest'
+import { expect } from 'vitest'
+import { analyze } from '../index.js'
+
+test('finds simple values', () => {
+	const fixture = `
+    test {
+      z-index: 1;
+      z-index: 0;
+      z-index: -1;
+      z-index: 99999;
+      z-index: -100;
+      z-index: 0;
+      z-index: auto;
+      z-index: calc(var(--model-z-index) - 1);
+    }
+  `
+	const actual = analyze(fixture).values.zindexes
+	const expected = {
+		total: 7,
+		totalUnique: 6,
+		unique: {
+			'0': 2,
+			'1': 1,
+			'99999': 1,
+			'-1': 1,
+			'-100': 1,
+			'calc(var(--model-z-index) - 1)': 1,
+		},
+		uniquenessRatio: 6 / 7,
+	}
+
+	expect(actual).toEqual(expected)
+})
+
+test('ignores global CSS keywords', () => {
+	const fixture = `
+    test {
+      z-index: auto;
+
+      /* Global values */
+      z-index: inherit;
+      z-index: initial;
+      z-index: revert;
+      z-index: revert-layer;
+      z-index: unset;
+    }
+  `
+	const actual = analyze(fixture).values.zindexes
+	const expected = {
+		total: 0,
+		totalUnique: 0,
+		unique: {},
+		uniquenessRatio: 0,
+	}
+
+	expect(actual).toEqual(expected)
+})
diff --git a/src/vendor-prefix.js b/src/vendor-prefix.js
deleted file mode 100644
index 696ba3df..00000000
--- a/src/vendor-prefix.js
+++ /dev/null
@@ -1,20 +0,0 @@
-const HYPHENMINUS = 45; // '-'.charCodeAt()
-
-/**
- * @param {string} keyword
- * @returns {boolean}
- */
-function hasVendorPrefix(keyword) {
-  if (keyword.charCodeAt(0) === HYPHENMINUS && keyword.charCodeAt(1) !== HYPHENMINUS) {
-    // String must have a 2nd occurrence of '-', at least at position 3 (offset=2)
-    if (keyword.indexOf('-', 2) !== -1) {
-      return true
-    }
-  }
-
-  return false
-}
-
-export {
-  hasVendorPrefix
-}
\ No newline at end of file
diff --git a/src/vendor-prefix.ts b/src/vendor-prefix.ts
new file mode 100644
index 00000000..9c34f004
--- /dev/null
+++ b/src/vendor-prefix.ts
@@ -0,0 +1,12 @@
+const HYPHENMINUS = 45 // '-'.charCodeAt()
+
+export function hasVendorPrefix(keyword: string): boolean {
+	if (keyword.charCodeAt(0) === HYPHENMINUS && keyword.charCodeAt(1) !== HYPHENMINUS) {
+		// String must have a 2nd occurrence of '-', at least at position 3 (offset=2)
+		if (keyword.indexOf('-', 2) !== -1) {
+			return true
+		}
+	}
+
+	return false
+}
diff --git a/tsconfig.json b/tsconfig.json
index 31498cc8..d5184add 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -22,7 +22,7 @@
 		"lib": ["ES2022", "DOM", "DOM.Iterable"],
 	},
 	"include": [
-		"src/index.js"
+		"src/index.ts"
 	],
 	"exclude": ["node_modules"]
 }
\ No newline at end of file
diff --git a/vite.config.js b/vite.config.js
index 646d935d..c61a54b8 100644
--- a/vite.config.js
+++ b/vite.config.js
@@ -1,30 +1,26 @@
-import { resolve } from "path"
-import { defineConfig } from "vite"
-import dts from "vite-plugin-dts"
-import { codecovVitePlugin } from "@codecov/vite-plugin"
+import { resolve } from 'path'
+import { defineConfig } from 'vite'
+import dts from 'vite-plugin-dts'
+import { codecovVitePlugin } from '@codecov/vite-plugin'
 
 export default defineConfig({
 	build: {
 		lib: {
-			entry: resolve(__dirname, "src/index.js"),
+			entry: resolve(__dirname, 'src/index.js'),
 			formats: ['es'],
 		},
 		rollupOptions: {
 			// make sure to externalize deps that shouldn't be bundled
 			// into your library
-			external: [
-				"css-tree/parser",
-				"css-tree/walker",
-				"@bramus/specificity/core",
-			],
+			external: ['css-tree', 'css-tree/parser', 'css-tree/walker', '@bramus/specificity/core'],
 		},
 	},
 	plugins: [
 		dts(),
 		codecovVitePlugin({
 			enableBundleAnalysis: process.env.CODECOV_TOKEN !== undefined,
-			bundleName: "analyzeCss",
+			bundleName: 'analyzeCss',
 			uploadToken: process.env.CODECOV_TOKEN,
 		}),
 	],
-})
\ No newline at end of file
+})