build: bump tailwindcss from 4.1.6 to 4.1.8 in /demo

Bumps [tailwindcss](https://github.com/tailwindlabs/tailwindcss/tree/HEAD/packages/tailwindcss) from 4.1.6 to 4.1.8.
- [Release notes](https://github.com/tailwindlabs/tailwindcss/releases)
- [Changelog](https://github.com/tailwindlabs/tailwindcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/tailwindlabs/tailwindcss/commits/v4.1.8/packages/tailwindcss)

---
updated-dependencies:
- dependency-name: tailwindcss
  dependency-version: 4.1.8
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

demo/package-lock.json

@@ -17,7 +17,7 @@
     "@tailwindcss/vite": "^4.1.6",
     "autoprefixer": "^10.4.21",
     "prettier": "^3.5.3",
-    "tailwindcss": "^4.1.6",
+    "tailwindcss": "^4.1.8",
     "vite": "^6.3.5",
     "vite-plugin-node-polyfills": "^0.23.0"
   },