build(deps): bump tailwindcss from 3.4.19 to 4.3.0 (#15)

* build(deps): bump tailwindcss from 3.4.19 to 4.3.0

Bumps [tailwindcss](https://github.com/tailwindlabs/tailwindcss/tree/HEAD/packages/tailwindcss) from 3.4.19 to 4.3.0.
- [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/v4.3.0/packages/tailwindcss)

---
updated-dependencies:
- dependency-name: tailwindcss
  dependency-version: 4.3.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

* fix(styles): migrate to tailwindcss v4 with @tailwindcss/postcss plugin

* fix(styles): use @tailwind directives (v4-compat) instead of bare CSS @import

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: tiennm99 <tiennm99@outlook.com>

package.json

@@ -19,11 +19,12 @@
     "@sveltejs/adapter-static": "^3.0.8",
     "@sveltejs/kit": "^2.61.0",
     "@sveltejs/vite-plugin-svelte": "^7.0.0",
+    "@tailwindcss/postcss": "^4.3.0",
     "autoprefixer": "^10.4.0",
     "katex": "^0.17.0",
     "postcss": "^8.5.15",
     "svelte": "^5.55.9",
-    "tailwindcss": "^3.4.0",
+    "tailwindcss": "^4.3.0",
     "vite": "^8.0.14"
   },
   "devDependencies": {

postcss.config.js

@@ -1,6 +1,6 @@
 export default {
   plugins: {
-    tailwindcss: {},
+    '@tailwindcss/postcss': {},
     autoprefixer: {},
   },
 };