*{margin:0;padding:0;box-sizing:border-box}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif;line-height:1.6;color:#333;background-color:#f5f5f5}#app{max-width:800px;margin:0 auto;padding:2rem;text-align:center}h1{color:#2c3e50;margin-bottom:1rem;font-size:2.5rem}p{margin-bottom:2rem;font-size:1.1rem;color:#666}button{background-color:#3498db;color:#fff;border:none;padding:12px 24px;font-size:1rem;border-radius:6px;cursor:pointer;transition:background-color .3s ease}button:hover{background-color:#2980b9}button:active{transform:translateY(1px)}