replaced the hardcoded :first-child/:not(:last-child) rules with :nth-child(Nn+1)/:nth-child(Nn) math scoped per breakpoint (5/3/2 columns), plus a single higher-specificity

app/not-found.tsx

@@ -0,0 +1,12 @@
+export default function NotFound() {
+  return (
+    <div style={{minHeight:'100dvh',display:'flex',flexDirection:'column',justifyContent:'center',maxWidth:'var(--container)',margin:'0 auto',padding:'0 var(--pad)'}}>
+      <div className="status-row"><span className="green-dot"></span>404</div>
+      <div className="hero-name">Page not<br/>found.</div>
+      <p className="hero-lead">The page you&rsquo;re looking for doesn&rsquo;t exist or has moved.</p>
+      <div className="btns">
+        <a href="/" className="btn btn-d">Back to home</a>
+      </div>
+    </div>
+  )
+}