diff --git a/.changeset/sharp-ears-wear.md b/.changeset/sharp-ears-wear.md
new file mode 100644
index 00000000..4ad32178
--- /dev/null
+++ b/.changeset/sharp-ears-wear.md
@@ -0,0 +1,9 @@
+---
+"@mincho-js/css": patch
+---
+
+## New
+- Add `VariantStyle` type for constrained variant styles
+
+## Changes
+- Allow nested selector in `globalCss` function
diff --git a/packages/css/src/css/index.ts b/packages/css/src/css/index.ts
index 1198e104..7df1ba3f 100644
--- a/packages/css/src/css/index.ts
+++ b/packages/css/src/css/index.ts
@@ -16,10 +16,91 @@ import { className, getDebugName } from "../utils.js";
 
 // == Global CSS ===============================================================
 export function globalCss(selector: string, rule: GlobalCSSRule) {
-  gStyle(selector, transform(rule) as GlobalStyleRule);
+  const transformedStyle = transform({
+    selectors: {
+      [selector]: {
+        ...rule
+      }
+    }
+  }) as CSSRule;
+
+  const { selectors, ...atRuleStyles } = transformedStyle;
+  if (selectors !== undefined) {
+    Object.entries(selectors).forEach(([selector, styles]) => {
+      gStyle(selector, styles as GlobalStyleRule);
+    });
+  }
+
+  if (atRuleStyles !== undefined) {
+    const otherStyles = hoistSelectors(atRuleStyles);
+    Object.entries(otherStyles.selectors).forEach(([atRule, atRuleStyles]) => {
+      gStyle(atRule, atRuleStyles as GlobalStyleRule);
+    });
+  }
 }
 export const globalStyle = globalCss;
 
+// TODO: Make more type-safe
+type UnknownObject = Record<string, unknown>;
+type CSSRuleMap = Record<string, CSSRule>;
+interface HoistResult {
+  selectors: CSSRuleMap;
+}
+
+function hoistSelectors(input: CSSRule): HoistResult {
+  const result: HoistResult = {
+    selectors: {}
+  };
+
+  function processAtRules(obj: UnknownObject, path: string[] = []) {
+    for (const key in obj) {
+      if (key === "selectors") {
+        // Hoist each selector when selectors are found
+        const selectors = obj[key] as CSSRuleMap;
+        for (const selector in selectors) {
+          if (!result.selectors[selector]) {
+            result.selectors[selector] = {};
+          }
+
+          // Create nested object structure based on current path
+          let current = result.selectors[selector] as UnknownObject;
+          for (let i = 0; i < path.length; i += 2) {
+            const atRule = path[i];
+            const condition = path[i + 1];
+
+            if (!current[atRule]) {
+              current[atRule] = {};
+            }
+            const atRuleObj = current[atRule] as UnknownObject;
+            if (!atRuleObj[condition]) {
+              atRuleObj[condition] = {};
+            }
+
+            current = atRuleObj[condition] as UnknownObject;
+          }
+
+          // Copy style properties
+          Object.assign(current, selectors[selector]);
+        }
+      } else if (typeof obj[key] === "object" && obj[key] !== null) {
+        // at-rule found (e.g: @media, @supports)
+        const atRules = obj[key] as UnknownObject;
+        for (const condition in atRules) {
+          // Add current at-rule and condition to path and recursively call
+          processAtRules(atRules[condition] as UnknownObject, [
+            ...path,
+            key,
+            condition
+          ]);
+        }
+      }
+    }
+  }
+
+  processAtRules(input as UnknownObject);
+  return result;
+}
+
 // == CSS ======================================================================
 export function css(style: ComplexCSSRule, debugId?: string) {
   return vStyle(transform(style), debugId);
diff --git a/packages/css/src/index.ts b/packages/css/src/index.ts
index f747da71..772abd7f 100644
--- a/packages/css/src/index.ts
+++ b/packages/css/src/index.ts
@@ -36,6 +36,7 @@ export {
 export { rules, recipe } from "./rules/index.js";
 export { createRuntimeFn } from "./rules/createRuntimeFn.js";
 export type {
+  VariantStyle,
   RulesVariants,
   RecipeVariants,
   RuntimeFn,
diff --git a/packages/css/src/rules/index.ts b/packages/css/src/rules/index.ts
index d0b348b3..382f25ab 100644
--- a/packages/css/src/rules/index.ts
+++ b/packages/css/src/rules/index.ts
@@ -26,7 +26,8 @@ import type {
   PropTarget,
   PropVars,
   Serializable,
-  VariantStringMap
+  VariantStringMap,
+  VariantStyle
 } from "./types.js";
 import {
   mapValues,
@@ -264,16 +265,16 @@ if (import.meta.vitest) {
           color: {
             brand: { color: "#FFFFA0" },
             accent: { color: "#FFE4B5" }
-          },
+          } satisfies VariantStyle<"brand" | "accent">,
           size: {
             small: { padding: 12 },
             medium: { padding: 16 },
             large: { padding: 24 }
-          },
+          } satisfies VariantStyle<"small" | "medium" | "large">,
           outlined: {
             true: { border: "1px solid black" },
             false: { border: "1px solid transparent" }
-          }
+          } satisfies VariantStyle<"true" | "false">
         }
       } as const;
       const result = rules(variants, debugId);
diff --git a/packages/css/src/rules/types.ts b/packages/css/src/rules/types.ts
index a340fe9f..23012747 100644
--- a/packages/css/src/rules/types.ts
+++ b/packages/css/src/rules/types.ts
@@ -31,6 +31,14 @@ export type Serializable =
 
 type RecipeStyleRule = ComplexCSSRule | string;
 
+export type VariantStyle<
+  VariantNames extends string,
+  CssRule extends RecipeStyleRule = RecipeStyleRule
+> = {
+  [VariantName in VariantNames]: CssRule;
+};
+
+// Same of VariantMap but for fast type checking
 export type VariantDefinitions = Record<string, RecipeStyleRule>;
 
 type BooleanMap<T> = T extends "true" | "false" ? boolean : T;
diff --git a/vitest.config.ts b/vitest.config.ts
new file mode 100644
index 00000000..ad4a4cca
--- /dev/null
+++ b/vitest.config.ts
@@ -0,0 +1,7 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+  test: {
+    projects: ["packages/*/vite.config.ts"],
+  }
+});
diff --git a/vitest.workspace.ts b/vitest.workspace.ts
deleted file mode 100644
index b7d8641f..00000000
--- a/vitest.workspace.ts
+++ /dev/null
@@ -1,3 +0,0 @@
-import { defineWorkspace } from "vitest/config";
-
-export default defineWorkspace(["packages/*"]);