feat: fixed header with hero section extending behind it

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

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

@@ -47,7 +47,7 @@
 </script>
 
 <header
-  class="sticky top-0 z-50 w-full backdrop-blur-xl shadow-[0_8px_32px_-4px_color-mix(in_oklab,var(--color-primary)_20%,transparent)]"
+  class="fixed top-0 z-50 w-full backdrop-blur-xl shadow-[0_8px_32px_-4px_color-mix(in_oklab,var(--color-primary)_20%,transparent)]"
 >
   <div class="container mx-auto px-4">
     <div class="flex items-center justify-evenly h-16">

packages/frontend/src/routes/+layout.svelte

@@ -65,7 +65,7 @@
   <Header authStatus={data.authStatus} />
 
   <!-- Main Content -->
-  <main class="min-h-screen">
+  <main class="min-h-screen pt-16">
     {@render children()}
   </main>
 

packages/frontend/src/routes/+page.svelte

@@ -13,7 +13,7 @@
 <Meta title={$_("home.hero.title")} description={$_("home.hero.description")} />
 
 <!-- Hero Section -->
-<section class="relative min-h-screen flex items-center justify-center overflow-hidden">
+<section class="relative min-h-screen -mt-16 flex items-center justify-center overflow-hidden">
   <div class="absolute inset-0 bg-gradient-to-br from-primary/20 via-accent/10 to-background"></div>
   <SexyBackground />