body { margin: 0; background: white; color: #222; font: 16px system-ui, sans-serif; }
main { max-width: 360px; margin: 64px auto; padding: 24px; }
label { display: block; margin: 16px 0; }
input { display: block; box-sizing: border-box; width: 100%; margin-top: 6px; padding: 10px; font: inherit; }
button { padding: 8px 20px; font: inherit; cursor: pointer; }
#error { color: #a00; }
[hidden] { display: none !important; }