:root { font-family: system-ui, -apple-system, 'Segoe UI', sans-serif; color-scheme: light; }
body { margin: 0; background: #f4f6f8; color: #172b27; }
main { max-width: 700px; margin: 7vh auto; padding: 32px; background: white; border: 1px solid #ddd; border-radius: 16px; line-height: 1.6; }
h1 { font-size: 1.6rem; margin-top: 0; }
button { background: #0c6c4a; color: white; border: 0; border-radius: 9px; padding: 12px 18px; font-weight: 600; cursor: pointer; }
button:disabled { opacity: .45; cursor: default; }