fix: hide mail sidebar header in Pro shell

components/layout/sidebar.tsx

@@ -930,7 +930,9 @@ export function Sidebar({
         className
       )}
     >
-      {/* Header */}
+      {/* Header — hidden in the Pro shell, which owns its own chrome and
+          would otherwise render an empty strip (no collapse, no switcher). */}
+      {!isEmbedded && (
         <div className={cn("flex items-center border-b border-border", isCollapsed ? "justify-center px-2 py-2" : "gap-1 px-2 py-2")}>
           <Button
             variant="ghost"
@@ -956,6 +958,7 @@ export function Sidebar({
             <AccountSwitcher variant="expanded" className="flex-1" />
           )}
         </div>
+      )}
 
       {!isCollapsed && <DemoBanner />}
       {!isCollapsed && <VacationBanner />}