fix: use segmented phone tabs

src/index.css

@@ -1171,3 +1171,18 @@ body {
     line-height: 1.1;
   }
 }
+
+/* Final phone shape: obvious 2x2 segmented tabs, no hidden/offscreen nav. */
+@media (max-width: 520px) {
+  .tab-bar {
+    display: grid;
+    grid-template-columns: repeat(2, minmax(0, 1fr));
+    gap: 0.35rem;
+  }
+
+  .tab {
+    width: 100%;
+    min-height: 2.45rem;
+    font-size: 0.86rem;
+  }
+}