Update site navigation and header styling

The styling for various components including site navigation and the site header has been updated. Changes include amendments to layout options, color, spacing, and border adaptations to provide better visibility and user interaction. The shadow on the top loading bar indicator has also been relocated to enhance the bar's visibility.

apps/web/app/(marketing)/layout.tsx

@@ -8,13 +8,13 @@ async function SiteLayout(props: React.PropsWithChildren) {
   const user = await getUser();
 
   return (
-    <div className={'flex flex-col'}>
+    <>
       <SiteHeader user={user} />
 
       {props.children}
 
       <SiteFooter />
-    </div>
+    </>
   );
 }