STYLED - Roll out the layered card system to the admin workspace

The double-layer AppCard look showcased in the UI Kit was only applied on
the public frontend; every admin surface was pinned to layer=single and
stayed flat. Convert the admin section/container cards to the default
layered look, keeping compact metric tiles, toolbars, image tiles and
nested leaf cards single.

Add AppCard contentClassName so content utilities (space-y-*, grid, flex)
keep applying to the inner shell after the switch to double layer.

app/_admin/maintenance/page.tsx

@@ -60,7 +60,7 @@ export default async function AdminMaintenancePage({
       headerDescription={copy.subtitle}
     >
       <MotionFade delay={0.1}>
-        <AppCard layer="single">
+        <AppCard>
           <CardContent className="space-y-4 p-6">
             <p className="text-sm text-muted-foreground">{copy.maintenanceText}</p>
             <div className="flex flex-wrap items-center gap-3">

app/_admin/portfolio/projects/[id]/page.tsx

@@ -104,7 +104,7 @@ export default async function AdminPortfolioProjectPage({
         </MotionFade>
 
         <MotionFade delay={0.2}>
-          <AppCard level={2} layer="single">
+          <AppCard level={2}>
             <CardContent className="flex flex-col gap-4 p-6 lg:flex-row lg:items-center lg:justify-between">
               <div>
                 <p className="text-sm font-medium text-foreground">{copy.dangerZone}</p>

components/admin/marquee-settings-form.tsx

@@ -29,7 +29,7 @@ export function MarqueeSettingsForm({
 
       <div className="grid gap-4 xl:grid-cols-4">
         {rowMeta.map((row) => (
-          <AppCard key={`de-${row.key}`} level={2} layer="single" padding="sm" className="space-y-2">
+          <AppCard key={`de-${row.key}`} level={2} padding="sm" contentClassName="space-y-2">
             <Label htmlFor={`${row.key}-de`} className="text-sm font-semibold text-foreground">{row.label}</Label>
             <Textarea
               id={`${row.key}-de`}

components/admin/media-field-picker.tsx

@@ -89,7 +89,7 @@ export function MediaFieldPicker({
   }, [serializedValue]);
 
   return (
-    <AppCard level={2} layer="single" padding="sm" className="space-y-4">
+    <AppCard level={2} padding="sm" contentClassName="space-y-4">
       <input ref={hiddenInputRef} type="hidden" name={inputName} value={serializedValue} />
 
       <div className="flex items-start justify-between gap-4">

components/admin/media-library-manager.tsx

@@ -486,7 +486,7 @@ export function MediaLibraryManager({
         )
       ) : (
         <MotionFade delay={0.18}>
-          <AppCard layer="single">
+          <AppCard>
             <CardContent className="p-6 text-sm text-muted-foreground">
               {copy.empty}
             </CardContent>

components/admin/portfolio-categories-manager.tsx

@@ -110,7 +110,7 @@ function CategoryLocaleFields({
           const descriptionKey = `description${locale.key}` as const;
 
           return (
-            <AppCard key={`${idPrefix}-${locale.key}`} level={2} layer="single" padding="sm" className="space-y-4 rounded-nested">
+            <AppCard key={`${idPrefix}-${locale.key}`} level={2} padding="sm" className="rounded-nested" contentClassName="space-y-4">
               <p className="text-sm font-medium text-foreground">{locale.label}</p>
 
               <div className="space-y-2">
@@ -168,7 +168,7 @@ function CategoryStatusFields({
       </div>
 
       <div className="grid gap-4 lg:grid-cols-[minmax(0,1fr)_220px]">
-        <AppCard level={2} layer="single" padding="sm" className="rounded-nested">
+        <AppCard level={2} padding="sm" className="rounded-nested">
           <div className="flex items-start gap-3">
             {isActive ? (
               <ShieldCheck className="mt-0.5 h-4 w-4 text-status-success" />
@@ -395,7 +395,7 @@ export function PortfolioCategoriesManager({
               <DialogDescription>{copy.modalDescription}</DialogDescription>
             </DialogHeader>
 
-            <AppCard level={2} layer="single" padding="sm" className="rounded-nested">
+            <AppCard level={2} padding="sm" className="rounded-nested">
               <div className="grid gap-3 sm:grid-cols-3">
                 <div className="space-y-1">
                   <p className="text-sm font-medium text-foreground">1. Basics</p>
@@ -426,7 +426,7 @@ export function PortfolioCategoriesManager({
         </Dialog>
       </div>
 
-      <AppCard level={3} layer="single">
+      <AppCard level={3}>
         <CardContent className="space-y-4 p-6">
           <div className="flex items-center gap-3">
             <Layers3 className="h-5 w-5 text-brand-primary" />

components/admin/portfolio-project-form.tsx

@@ -528,7 +528,7 @@ export function PortfolioProjectForm({
 
   if (!project && availableCategories.length === 0) {
     return (
-      <AppCard level={3} layer="single" padding="lg" className="rounded-surface">
+      <AppCard level={3} padding="lg" className="rounded-surface">
         <div className="space-y-4">
           <div className="space-y-2">
             <p className="text-xs uppercase tracking-[0.18em] text-muted-foreground">Portfolio Setup</p>
@@ -577,7 +577,7 @@ export function PortfolioProjectForm({
       <input ref={assetsInputRef} type="hidden" name="assets" value={assetsPayload} />
       <input ref={intentRef} type="hidden" name="intent" defaultValue="save" />
 
-      <AppCard level={3} layer="single" padding="lg" className="space-y-6">
+      <AppCard level={3} padding="lg" contentClassName="space-y-6">
         <div className="flex flex-col gap-6">
           <div className="flex flex-col gap-4 lg:flex-row lg:items-start lg:justify-between">
             <div className="space-y-3">
@@ -625,7 +625,7 @@ export function PortfolioProjectForm({
 
       <div className="space-y-6">
         <div>
-          <AppCard level={3} layer="single" padding="lg">
+          <AppCard level={3} padding="lg">
             <section className="space-y-6">
               <SectionHeader
                 title="Basic Information"
@@ -787,7 +787,7 @@ export function PortfolioProjectForm({
         </div>
 
         <div>
-          <AppCard level={3} layer="single" padding="lg">
+          <AppCard level={3} padding="lg">
             <section className="space-y-6">
               <SectionHeader
                 title="Localized Content"
@@ -838,7 +838,7 @@ export function PortfolioProjectForm({
         </div>
 
         <div>
-          <AppCard level={3} layer="single" padding="lg">
+          <AppCard level={3} padding="lg">
             <section className="space-y-6">
               <SectionHeader
                 title="Sections"
@@ -1028,7 +1028,7 @@ export function PortfolioProjectForm({
         </div>
 
         <div>
-          <AppCard level={3} layer="single" padding="lg">
+          <AppCard level={3} padding="lg">
             <div className="space-y-8">
               <div className="grid gap-4 lg:grid-cols-[minmax(0,1fr)_280px]">
                 <div className="space-y-6">
@@ -1203,7 +1203,7 @@ export function PortfolioProjectForm({
         </div>
       </div>
 
-      <AppCard level={3} layer="single" padding="lg">
+      <AppCard level={3} padding="lg">
         <div className="flex flex-col gap-4 md:flex-row md:items-center md:justify-end">
           <div className="flex flex-wrap items-center gap-3">
             {firstIncompleteStep ? (

components/admin/portfolio-projects-overview.tsx

@@ -85,7 +85,7 @@ export async function PortfolioProjectsOverview({
       <div className="grid gap-4 xl:grid-cols-2">
         {projects.map((project, index) => (
           <MotionFade key={project.id} delay={0.06 + index * 0.03}>
-            <AppCard interactive layer="single" className="h-full">
+            <AppCard interactive className="h-full">
               <CardContent className="flex flex-col gap-4 p-5 lg:flex-row lg:items-center lg:justify-between">
                 <div className="space-y-2">
                   <div className="flex flex-wrap items-center gap-2">
@@ -122,7 +122,7 @@ export async function PortfolioProjectsOverview({
         ))}
 
         {projects.length === 0 ? (
-          <AppCard layer="single" className="xl:col-span-2">
+          <AppCard className="xl:col-span-2">
             <CardContent className="p-6 text-sm text-muted-foreground">
               {copy.empty}
             </CardContent>

components/admin/site-settings-form.tsx

@@ -270,7 +270,7 @@ function SiteSettingsMediaRow({
 
   return (
     <>
-      <AppCard level={2} layer="single" padding="sm">
+      <AppCard level={2} padding="sm">
         <div className="grid gap-4 lg:grid-cols-[180px_minmax(0,1fr)]">
           <div className="space-y-2">
             <p className="text-sm font-semibold text-foreground">{title}</p>
@@ -393,7 +393,7 @@ function LocalizedFieldsSection({
 
       <div className="grid gap-5 lg:grid-cols-3">
         {localeFields.map((locale) => (
-          <AppCard key={locale.key} level={2} layer="single" padding="sm" className="space-y-4">
+          <AppCard key={locale.key} level={2} padding="sm" contentClassName="space-y-4">
             <p className="text-sm font-semibold text-foreground">{locale.label}</p>
 
             <div className="space-y-2">
@@ -558,7 +558,7 @@ export function SiteSettingsForm({
                   </p>
                 </div>
 
-                <AppCard level={2} layer="single" padding="sm" className="space-y-4">
+                <AppCard level={2} padding="sm" contentClassName="space-y-4">
                   <div className="grid gap-4 lg:grid-cols-[minmax(0,1fr)_220px]">
                     <div className="space-y-2">
                       <Label htmlFor="primaryColor" className="sr-only">Primary Color</Label>
@@ -679,7 +679,7 @@ export function SiteSettingsForm({
                   </p>
                 </div>
 
-                <AppCard level={2} layer="single" padding="sm" className="space-y-4">
+                <AppCard level={2} padding="sm" contentClassName="space-y-4">
                   <div className="grid gap-4 lg:grid-cols-[minmax(0,1fr)_minmax(0,1fr)]">
                     <div className="space-y-2">
                       <Label htmlFor="defaultLocaleTrigger" className="sr-only">Default Locale</Label>
@@ -729,7 +729,7 @@ export function SiteSettingsForm({
           <section className="space-y-4">
             {mode === "brand" ? (
               <>
-                <AppCard level={2} layer="single" padding="sm" className="space-y-2">
+                <AppCard level={2} padding="sm" contentClassName="space-y-2">
                   <p className="text-xs uppercase tracking-[0.14em] text-muted-foreground">Search Result</p>
                   <div className="rounded-nested border border-border/70 bg-background p-3">
                     <div className="flex items-center gap-3">
@@ -750,7 +750,7 @@ export function SiteSettingsForm({
                   </div>
                 </AppCard>
 
-                <AppCard level={2} layer="single" padding="sm" className="space-y-2">
+                <AppCard level={2} padding="sm" contentClassName="space-y-2">
                   <p className="text-xs uppercase tracking-[0.14em] text-muted-foreground">Brand Assets</p>
                   <div className="grid gap-3 sm:grid-cols-2">
                     <AppCard level={1} layer="single" padding="sm">
@@ -773,7 +773,7 @@ export function SiteSettingsForm({
                   </div>
                 </AppCard>
 
-                <AppCard level={2} layer="single" padding="sm" className="space-y-2">
+                <AppCard level={2} padding="sm" contentClassName="space-y-2">
                   <p className="text-xs uppercase tracking-[0.14em] text-muted-foreground">Social Preview</p>
                   <div className="overflow-hidden rounded-nested border border-border/70 bg-background">
                     <div className="h-1.5" style={{ backgroundColor: settings.brand.primaryColor }} />
@@ -797,7 +797,7 @@ export function SiteSettingsForm({
               </>
             ) : (
               <>
-                <AppCard level={2} layer="single" padding="sm" className="space-y-2">
+                <AppCard level={2} padding="sm" contentClassName="space-y-2">
                   <p className="text-xs uppercase tracking-[0.14em] text-muted-foreground">Visitor Routing</p>
                   <div className="rounded-nested border border-border/70 bg-background p-3">
                     <div className="flex items-center gap-2 text-sm font-medium text-foreground">
@@ -810,7 +810,7 @@ export function SiteSettingsForm({
                   </div>
                 </AppCard>
 
-                <AppCard level={2} layer="single" padding="sm" className="space-y-2">
+                <AppCard level={2} padding="sm" contentClassName="space-y-2">
                   <p className="text-xs uppercase tracking-[0.14em] text-muted-foreground">Locale Summary</p>
                   <div className="rounded-nested border border-border/70 bg-background">
                     <Table>

components/admin/smtp-settings-form.tsx

@@ -25,7 +25,7 @@ export function SMTPSettingsForm({
   return (
     <form id="smtp-settings-form" action={action} className="space-y-6">
       <div className="grid gap-6 xl:grid-cols-2">
-        <AppCard layer="single">
+        <AppCard>
           <CardHeader>
             <CardTitle>SMTP Connection</CardTitle>
             <CardDescription>Server und Login.</CardDescription>
@@ -109,7 +109,7 @@ export function SMTPSettingsForm({
           </CardContent>
         </AppCard>
 
-        <AppCard layer="single">
+        <AppCard>
           <CardHeader>
             <CardTitle>Sender And Recipients</CardTitle>
             <CardDescription>Absender und Ziele.</CardDescription>

components/admin/workspace-patterns.tsx

@@ -17,7 +17,7 @@ export function WorkspaceHero({
   aside?: ReactNode;
 }) {
   return (
-    <AppCard level={3} layer="single">
+    <AppCard level={3}>
       <CardContent className="flex flex-col gap-4 p-6 lg:flex-row lg:items-end lg:justify-between lg:p-8">
         <div className="space-y-2">
           <p className="text-xs font-semibold uppercase tracking-[0.14em] text-muted-foreground">
@@ -40,7 +40,7 @@ export function WorkspaceSidebarPanel({
   children: ReactNode;
 }) {
   return (
-    <AppCard level={2} layer="single">
+    <AppCard level={2}>
       <CardHeader className="pb-4">
         <CardTitle className="text-base">{title}</CardTitle>
       </CardHeader>
@@ -100,7 +100,7 @@ export function WorkspaceLocaleCard({
   children: ReactNode;
 }) {
   return (
-    <AppCard level={2} layer="single">
+    <AppCard level={2}>
       <CardHeader className="pb-4">
         <CardTitle className="text-lg">{title}</CardTitle>
         <CardDescription>{hint}</CardDescription>

components/ui/app-card.tsx

@@ -87,10 +87,21 @@ export interface AppCardProps
     VariantProps<typeof appCardVariants>,
     VariantProps<typeof appCardInnerVariants> {
   layer?: "double" | "single";
+  /**
+   * Classes applied to the element that directly wraps `children` (the inner
+   * shell in `double` layer, the single shell in `single` layer). Use it for
+   * content utilities such as `space-y-*` / `grid` / `flex` so they keep
+   * working after switching a card to the layered (double) look, where
+   * `className` lands on the outer shell instead.
+   */
+  contentClassName?: string;
 }
 
 const AppCard = React.forwardRef<HTMLDivElement, AppCardProps>(
-  ({ className, level, padding, interactive, layer = "double", children, ...props }, ref) => {
+  (
+    { className, contentClassName, level, padding, interactive, layer = "double", children, ...props },
+    ref,
+  ) => {
     if (layer === "single") {
       return (
         <Card
@@ -102,6 +113,7 @@ const AppCard = React.forwardRef<HTMLDivElement, AppCardProps>(
               interactive,
             }),
             className,
+            contentClassName,
           )}
           {...props}
         >
@@ -129,6 +141,7 @@ const AppCard = React.forwardRef<HTMLDivElement, AppCardProps>(
               padding,
               interactive,
             }),
+            contentClassName,
           )}
         >
           {children}