*{box-sizing:border-box;margin:0;padding:0}body{font-family:Segoe UI,Tahoma,Geneva,Verdana,sans-serif;text-align:center;line-height:1.6;background-color:#f5f5f5}h1,h2,h3,h4{margin-bottom:1rem;font-weight:600;color:#2c3e50}button{background-color:#3498db;color:#fff;border:none;padding:10px 20px;border-radius:5px;cursor:pointer;font-size:14px;font-weight:500;transition:background-color .3s ease;margin:5px}button:hover{background-color:#2980b9}