:root { font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif; }
body { max-width: 720px; margin: 40px auto; padding: 0 16px; line-height: 1.35; }
header { margin-bottom: 20px; }
nav a { margin-right: 12px; }
.card { border: 1px solid #ddd; border-radius: 10px; padding: 18px; margin: 16px 0; }
label { display: block; margin-top: 12px; font-weight: 600; }
input { width: 100%; padding: 10px; margin-top: 6px; font-size: 16px; }
button { margin-top: 16px; padding: 10px 14px; font-size: 16px; cursor: pointer; }
.hint { color: #555; font-size: 14px; margin-top: 8px; }
.code { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; background: #f6f6f6; padding: 2px 6px; border-radius: 6px; }
footer { margin-top: 30px; color: #666; font-size: 13px; }