body{font-family:system-ui;background:#f5f5f5;margin:0;}
.topbar{background:#283593;color:white;padding:10px 20px;display:flex;justify-content:space-between;}
.container{max-width:1100px;margin:20px auto;background:white;padding:20px;border-radius:8px;}
.btn-3d{background:linear-gradient(#4caf50,#2e7d32);color:#fff;padding:8px 14px;border:none;border-radius:8px;box-shadow:0 4px #1b5e20;}