Simplify settings workspace and fix responsive admin controls

frontend/app/globals.css

@@ -6435,7 +6435,8 @@ textarea {
   }
 }
 
-/* Final header account menu stacking override (must be last) */
+/* Keep the account menu above header controls. Header positioning is owned
+   by the responsive application shell in ops-redesign.css. */
 .page,
 .header,
 .header-left,
@@ -6447,9 +6448,7 @@ textarea {
 }
 
 .header {
-  position: relative !important;
   isolation: isolate;
-  z-index: 20 !important;
 }
 
 .header-nav,