feat: Implement expandable specialization cards with an overlay, update specialization section grid item alignment, and reposition common header navigation.

src/components/layout/CommonHeader.tsx

@@ -70,8 +70,8 @@ export function CommonHeader() {
           />
         </Link>
 
-        {/* Navigation - Desktop only (centered absolutely) */}
-        <nav className="hidden md:flex items-center gap-8 absolute left-1/2 -translate-x-1/2">
+        {/* Navigation - Desktop only */}
+        <nav className="hidden md:flex items-center gap-8 ml-auto mr-8">
           {navLinks.map((link) => (
             <Link
               key={link.href}