Fix Super Admin page content rendering under the fixed header

Header is position: fixed (h-16) and SuperAdminPage never offset its
content for that, so the onboarding form rendered underneath the
purple header bar. Add pt-16 to match how the rest of the app already
compensates for this same fixed header, and constrain content width
instead of stretching full-viewport.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/components/SuperAdminPage.tsx

@@ -26,7 +26,7 @@ export default function SuperAdminPage({ user, onLogout }: SuperAdminPageProps)
   const profile = { name: user.name, role: 'Super Admin', email: user.email };
 
   return (
-    <div className="min-h-screen bg-slate-50 flex flex-col">
+    <div className="min-h-screen bg-slate-50">
       <Header
         isSidebarOpen={false}
         onToggleSidebar={() => {}}
@@ -34,7 +34,8 @@ export default function SuperAdminPage({ user, onLogout }: SuperAdminPageProps)
         onLogoutClick={onLogout}
         profile={profile}
       />
-      <main className="flex-1 p-4 md:p-6">
+      {/* Header is fixed (h-16); pt-16 keeps content from rendering under it. */}
+      <main className="pt-16 p-4 md:p-6 max-w-6xl mx-auto">
         <Routes>
           <Route path="onboarding" element={<AdminConsole showHeader />} />
           <Route path="*" element={<Navigate to="onboarding" replace />} />