fix: 타이틀바 배경이 투명한 문제 해결

src/pages/Root.tsx

@@ -9,7 +9,7 @@ export default function Root() {
     <SidebarProvider>
       <AppSidebar />
       <SidebarInset>
-        <header className="flex sticky top-0 bg-white h-16 shrink-0 items-center gap-2 border-b px-4">
+        <header className="flex sticky top-0 bg-white h-16 shrink-0 items-center gap-2 border-b px-4 z-10">
           <SidebarTrigger className="-ml-1" />
           <Separator orientation="vertical" className="mr-2 h-4" />
           <Link to="/" className="text-lg md:text-base font-semibold whitespace-nowrap">