body{font-family:sans-serif;margin:0;padding:0;background:#f9fafb;} .topbar{background:#1e3a8a;color:#fff;padding:1rem;} .main{padding:1rem;} .footer{background:#eee;padding:1rem;text-align:center;} .nav.hidden{display:none;} .nav{background:#ddd;padding:0.5rem;} .nav-link{margin-right:1rem;}