*{box-sizing:border-box}body{font-family:system-ui,-apple-system,Segoe UI,Roboto,Apple SD Gothic Neo,Malgun Gothic,sans-serif;margin:0;color:#111;background:#fff}
header,footer{background:#f8f9fb;border-bottom:1px solid #e9eef3}
.container{max-width:900px;margin:0 auto;padding:16px}
header h1{margin:0 0 8px 0}
nav a{margin-right:12px;text-decoration:none;color:#3366cc}
nav a:hover{text-decoration:underline}
.hero{padding:16px;background:#eef5ff;border:1px solid #d8e7ff;border-radius:12px}
.document{line-height:1.7}
footer{border-top:1px solid #e9eef3}