refactor: Migrate from tailwind.js config to Tailwind CSS config (#451)

* refactor: Migrate from tailwind.js config to Tailwind CSS configuration and improve component styling

- Removed extensive theme and animation configurations from tailwind.config.js, migrating them to index.css for better organization.
- Updated components to utilize CSS variables for grid layouts and animations, enhancing maintainability.
- Adjusted various components to reflect the new CSS structure, ensuring consistent styling across the application.
- Improved accessibility and responsiveness in several UI components, including headers and popovers.
- Fixed minor styling issues and optimized class usage for better performance.

* style: use default tailwindcss/forms options

* refactor(Header): remove unused LuUser icon import

ui/src/components/sidebar/connectionStats.tsx

@@ -99,7 +99,7 @@ export default function ConnectionStatsSidebar() {
   }, 500);
 
   return (
-    <div className="grid h-full grid-rows-headerBody shadow-xs">
+    <div className="grid h-full grid-rows-(--grid-headerBody) shadow-xs">
       <SidebarHeader title="Connection Stats" setSidebarView={setSidebarView} />
       <div className="h-full space-y-4 overflow-y-scroll bg-white px-4 py-2 pb-8 dark:bg-slate-900">
         <div className="space-y-4">