feat(themes): Added custom theme support.

package.json

@@ -61,6 +61,7 @@
     "zod": "^3.22.4"
   },
   "devDependencies": {
+    "@tailwindcss/postcss": "^4.0.0",
     "@types/better-sqlite3": "^7.6.12",
     "@types/html-to-text": "^9.0.4",
     "@types/jsdom": "^21.1.7",
@@ -77,7 +78,7 @@
     "eslint-config-next": "14.1.4",
     "postcss": "^8",
     "prettier": "^3.2.5",
-    "tailwindcss": "^3.3.0",
+    "tailwindcss": "^4.0.0",
     "typescript": "^5"
   }
 }