*{box-sizing:border-box}body{font-family:Arial,sans-serif;padding:20px;background:#f7fafc}.container{max-width:640px;margin:0 auto;background:#fff;padding:20px;border-radius:8px;box-shadow:0 6px 18px #0000000f}.form{display:flex;gap:8px;margin-bottom:12px}.form input{flex:1;padding:8px}.form button{padding:8px 12px}.list{list-style:none;padding:0}.list li{padding:8px 0;border-bottom:1px solid #eee}.error{color:#b00020;margin:8px 0}.note{margin-top:12px;font-size:12px;color:#666}