body{font-family:Arial,sans-serif;background:#f4f4f4;margin:40px}
.card{background:#fff;padding:16px;margin:16px 0;border-radius:8px;box-shadow:0 2px 6px #0002}
button{padding:8px 14px}
pre{background:#222;color:#0f0;padding:10px;white-space:pre-wrap}