Refactor styles and remove Tailwind configuration

- Deleted postcss.config.mjs as it is no longer needed.
- Updated Layout.astro to reference main.css instead of using @tailwind components.
- Modified expressive-code.css to include a reference to Tailwind CSS.
- Reworked main.css to use @import for Tailwind and added custom variants and utilities.
- Updated markdown.css to reference main.css and adjusted anchor styles.
- Enhanced photoswipe.css and scrollbar.css with Tailwind references and applied important modifiers.
- Updated transition.css to include Tailwind reference.
- Removed tailwind.config.cjs as part of the cleanup.

package.json

@@ -20,7 +20,6 @@
     "@astrojs/rss": "^4.0.12",
     "@astrojs/sitemap": "^3.4.1",
     "@astrojs/svelte": "7.1.0",
-    "@astrojs/tailwind": "^6.0.2",
     "@expressive-code/core": "^0.41.3",
     "@expressive-code/plugin-collapsible-sections": "^0.41.3",
     "@expressive-code/plugin-line-numbers": "^0.41.3",
@@ -33,6 +32,7 @@
     "@iconify/svelte": "^4.2.0",
     "@swup/astro": "^1.7.0",
     "@tailwindcss/typography": "^0.5.16",
+    "@tailwindcss/vite": "^4.1.11",
     "astro": "5.12.3",
     "astro-expressive-code": "^0.41.3",
     "astro-icon": "^1.1.5",
@@ -57,7 +57,7 @@
     "sharp": "^0.34.3",
     "stylus": "^0.64.0",
     "svelte": "^5.36.16",
-    "tailwindcss": "^3.4.17",
+    "tailwindcss": "^4.1.11",
     "typescript": "^5.8.3",
     "unist-util-visit": "^5.0.0"
   },