diff --git a/admin-spa/src/App.tsx b/admin-spa/src/App.tsx
index 2d6f1c4..e19bdc7 100644
--- a/admin-spa/src/App.tsx
+++ b/admin-spa/src/App.tsx
@@ -335,7 +335,7 @@ function Header({ onFullscreen, fullscreen, showToggle = true, scrollContainerRe
   }
   
   return (
-    <header className={`h-16 border-b border-border flex items-center px-4 justify-between md:sticky ${fullscreen ? `md:top-0 fixed top-0 left-0 right-0` : `top-[32px]`} z-40 bg-background md:bg-background/95 md:backdrop-blur md:supports-[backdrop-filter]:bg-background/60 transition-transform duration-300 ${!isVisible ? '-translate-y-full md:translate-y-0' : 'translate-y-0'}`}>
+    <header className={`h-16 border-b border-border flex items-center px-4 justify-between sticky ${fullscreen ? `top-0` : `top-[32px]`} z-40 bg-background md:bg-background/95 md:backdrop-blur md:supports-[backdrop-filter]:bg-background/60 transition-transform duration-300 ${fullscreen && !isVisible ? '-translate-y-full md:translate-y-0' : 'translate-y-0'}`}>
       <div className="font-semibold">{siteTitle}</div>
       <div className="flex items-center gap-3">
         <div className="text-sm opacity-70 hidden sm:block">{window.WNW_API?.isDev ? 'Dev Server' : 'Production'}</div>
diff --git a/admin-spa/src/components/PageHeader.tsx b/admin-spa/src/components/PageHeader.tsx
index c5ef39d..61c488f 100644
--- a/admin-spa/src/components/PageHeader.tsx
+++ b/admin-spa/src/components/PageHeader.tsx
@@ -10,13 +10,10 @@ export function PageHeader({ fullscreen = false }: PageHeaderProps) {
 
   if (!title) return null;
 
-  // Calculate top position based on fullscreen state
-  // Fullscreen: top-0 (submenu is at top-0)
-  // Normal: top-[calc(7rem+32px)] = top-[144px] (below WP bar + menu + submenu)
-  const topClass = fullscreen ? 'top-0' : 'top-[calc(10rem+32px)]';
-
+  // PageHeader sticks at top-0 and naturally stacks below submenu (which has z-20)
+  // Our z-10 ensures we're below the submenu in stacking order
   return (
-    <div className={`sticky ${topClass} z-10 border-b bg-background`}>
+    <div className="sticky top-0 z-10 border-b bg-background">
       <div className="w-full max-w-5xl mx-auto px-4 py-3 flex items-center justify-between min-w-0">
         <div className="min-w-0 flex-1">
           <h1 className="text-lg font-semibold truncate">{title}</h1>