:root { color-scheme: light dark; --accent: #2563eb; }
body { margin: 0; font: 17px/1.5 -apple-system, BlinkMacSystemFont, "Helvetica Neue", sans-serif; }
main { max-width: 32rem; margin: 3rem auto; padding: 0 1rem; text-align: center; }
.btn { display: block; margin: 1.5rem auto 0; padding: 1rem 1.25rem; border-radius: 12px; background: var(--accent); color: #fff; font-size: 1.25rem; font-weight: 600; text-decoration: none; }
.btn:active { opacity: 0.8; }
.btn[hidden], .hint[hidden] { display: none; }
.hint { font-size: 0.95rem; opacity: 0.75; }