fix: correct mobile menu background placement with blur effect

Move background styling from outer overlay to inner container for proper visibility.
- Remove bg-background from outer fixed div
- Add bg-background/95 backdrop-blur-md h-full to inner container
- Creates frosted glass effect with proper blur

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

components/layout/Navbar.tsx

@@ -116,8 +116,8 @@ export function Navbar() {
 
       {/* Mobile Menu Drawer */}
       {mobileMenuOpen && (
-        <div className="md:hidden fixed inset-0 top-16 z-50 bg-background">
-          <div className="container px-4 py-6">
+        <div className="md:hidden fixed inset-0 top-16 z-50">
+          <div className="container px-4 py-6 bg-background/95 backdrop-blur-md h-full">
             <nav className="flex flex-col gap-2">
               {navItems.map((item) => (
                 <Link key={item.href} href={item.href}>