:root { --maxw: 720px; }
html, body { margin: 0; padding: 0; }
body { font-family: system-ui, -apple-system, Segoe UI, Roboto, sans-serif; line-height: 1.5; }
main { max-width: var(--maxw); margin: 6rem auto; padding: 1rem; }
.btn { display: inline-block; padding: .5rem .75rem; border-radius: .5rem; border: 1px solid #e5e7eb; text-decoration: none; }
[hidden] { display: none !important; }