*{box-sizing:border-box;margin:0;padding:0;font-family:Arial,sans-serif}body{color:#333;background:#f5f7fa}header,footer{color:#fff;text-align:center;background:#0a2540;padding:1.5rem}nav a{color:#fff;margin:0 1rem;font-weight:700;text-decoration:none}section{max-width:1000px;margin:auto;padding:3rem 2rem}