body { font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; background: #f6f8fa; color: #1f2328; }
main { max-width: 640px; margin: 80px auto; padding: 32px; background: #fff; border: 1px solid #d0d7de; border-radius: 12px; }
button { padding: 8px 16px; color: #fff; background: #1f883d; border: 0; border-radius: 6px; cursor: pointer; }