body{margin:0;font-family:Segoe UI,Tahoma,Geneva,Verdana,sans-serif;background-color:#f4f6f8;color:#333}h1,h2{color:#2c3e50;text-align:center}.app{max-width:600px;height:92vh;margin:5px auto auto;background:#fff;padding:2rem;border-radius:12px;box-shadow:0 4px 10px #0000001a}ul,ol{padding-left:20px}button{background-color:#3498db;color:#fff;padding:.5rem 1rem;border:none;border-radius:6px;cursor:pointer;font-size:1rem;margin-top:1rem}button:hover{background-color:#2980b9}input[type=text]{padding:.5rem;border:1px solid #ccc;border-radius:6px;margin-right:.5rem;width:60%}