body { font-family: sans-serif; background: #f4f4f4; margin: 0; padding: 0; }
.container { max-width: 700px; margin: 40px auto; background: white; padding: 20px; border-radius: 8px;
box-shadow: 0 0 10px #ccc; }
button, select { padding: 10px; width: 100%; margin: 6px 0; }
pre { background: #eee; padding: 10px; height: 200px; overflow-y: auto; }