style: reduce header background opacity for softer appearance

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

packages/frontend/package.json

@@ -30,7 +30,6 @@
     "glob": "^13.0.6",
     "mode-watcher": "^1.1.0",
     "prettier-plugin-svelte": "^3.5.1",
-
     "svelte": "^5.53.7",
     "svelte-check": "^4.4.4",
     "svelte-sonner": "^1.0.8",

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

@@ -47,7 +47,7 @@
 </script>
 
 <header
-  class="sticky top-0 z-50 w-full bg-gradient-to-br from-card/85 via-card/90 to-card/80 backdrop-blur-xl shadow-2xl shadow-primary/20"
+  class="sticky top-0 z-50 w-full bg-gradient-to-br from-card/60 via-card/65 to-card/55 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">