*,:before,:after{box-sizing:border-box;margin:0;padding:0}body{color:#222;background:#f4f7f6;font-family:system-ui,-apple-system,sans-serif}header{background:#fff;border-bottom:1px solid #ddd;padding:16px 24px}nav{gap:16px;display:flex}nav a{color:#333;font-weight:500;text-decoration:none}nav a:hover{color:#0070f3}main{padding:40px 24px}footer{text-align:center;background:#fff;border-top:1px solid #ddd;margin-top:40px;padding:24px}