body{font-family:system-ui,-apple-system,Segoe UI,Roboto,sans-serif;max-width:720px;margin:2rem auto;padding:0 1rem;line-height:1.6;color:#222}header{border-bottom:1px solid #ddd;margin-bottom:1rem}nav a{margin-right:.8rem}footer{margin-top:2rem;color:#666;font-size:.9em}