feat: enhance CSS handling and optimize global styles

- Enabled PostCSS nesting with specific configuration for modern compatibility
- Added global CSS reset for consistent tap highlights across browsers
- Optimized package configuration for broader browser support
- Refactored and streamlined global CSS, removing redundant styles for better maintainability
- Integrated additional CSS import in component for modular styling approach

postcss.config.cjs

@@ -1,6 +1,9 @@
 module.exports = {
   plugins: [
-    // require('postcss-nesting'),
+    require('postcss-nesting')({
+      edition: '2021',
+      noIsPseudoSelector: true,
+    }),
     require('autoprefixer'),
     require('cssnano'),
   ],