feat: add css key to vite config (#518)

apps/documentation/src/routes/documentation/configuration.mdx

@@ -45,6 +45,13 @@ Useful for configuring custom source alias paths during imports
   - `Array<{ find: string | RegExp, replacement: string, customResolver?: ResolverFunction | ResolverObject }>`
 - [Vite documentation: resolve.alias](https://vite.dev/config/shared-options#resolve-alias)
 
+### `vite.css                           `
+
+Config object for managing CSS behavior and integration with preprocessors (e.g., Sass, Less, etc.)
+
+- Type: `CSSOptions`
+- [Vite documentation: css](https://vite.dev/config/shared-options#css-modules)
+
 ### `vite.optimizeDeps`
 
 Vite's dependency optimizer used only during dev