style: transparent header, no scroll tracking

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/frontend/src/lib/components/header/header.svelte

@@ -19,13 +19,6 @@
   let { authStatus }: Props = $props();
 
   let isMobileMenuOpen = $state(false);
-  let scrolled = $state(false);
-
-  $effect(() => {
-    const onScroll = () => (scrolled = window.scrollY > 10);
-    window.addEventListener("scroll", onScroll, { passive: true });
-    return () => window.removeEventListener("scroll", onScroll);
-  });
 
   const navLinks = [
     { name: $_("header.home"), href: "/" },
@@ -54,7 +47,7 @@
 </script>
 
 <header
-  class={`sticky top-0 z-50 w-full backdrop-blur-xl transition-all duration-500 ${scrolled ? "bg-gradient-to-br from-card/85 via-card/90 to-card/80 shadow-2xl shadow-primary/20 border-b border-border/20" : "bg-transparent border-b border-transparent shadow-none"}`}
+  class="sticky top-0 z-50 w-full backdrop-blur-xl border-b border-border/20 shadow-lg shadow-primary/10"
 >
   <div class="container mx-auto px-4">
     <div class="flex items-center justify-evenly h-16">