Apply tailwindcss rules with `!important` (#29437)

As per discussion in https://github.com/go-gitea/gitea/pull/29423, I
think this is the right way that does not burden developers having to
think about CSS precedence which should be irrelevant with an atomic CSS
framework.

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

tailwind.config.js

@@ -6,6 +6,7 @@ const isProduction = env.NODE_ENV !== 'development';
 
 export default {
   prefix: 'tw-',
+  important: true, // the frameworks are mixed together, so tailwind needs to override other framework's styles
   content: [
     isProduction && '!./templates/devtest/**/*',
     isProduction && '!./web_src/js/standalone/devtest.js',