Revert "Migrate to HeroUI v3 and Tailwind CSS v4"

This reverts commit 6a9296f33d.

package.json

@@ -17,9 +17,6 @@
   "type": "module",
   "dependencies": {
     "@emotion/is-prop-valid": "^1.4.0",
-    "@heroui/react": "^3.0.0-beta.5",
-    "@heroui/styles": "^3.0.0-beta.5",
-    "@tailwindcss/postcss": "^4.1.18",
     "@vercel/og": "^0.8.5",
     "clsx": "^2.1.1",
     "contentlayer2": "^0.5.8",
@@ -38,19 +35,20 @@
     "remark-gfm": "^4.0.1",
     "shiki": "^3.15.0",
     "tailwind-merge": "^3.4.0",
-    "tailwind-variants": "^3.2.2",
     "unist-util-visit": "^5.0.0"
   },
   "devDependencies": {
+    "@tailwindcss/typography": "^0.5.19",
     "@types/node": "^24.10.1",
     "@types/react": "^19.2.5",
     "@types/react-dom": "^19.2.3",
+    "autoprefixer": "^10.4.22",
     "concurrently": "^9.2.1",
     "eslint": "^9.39.1",
     "eslint-config-next": "^16.0.3",
     "pagefind": "^1.4.0",
     "postcss": "^8.5.6",
-    "tailwindcss": "^4.1.18",
+    "tailwindcss": "^3.4.18",
     "typescript": "^5.9.3"
   }
 }