:root { font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial; color-scheme: light dark; }
body { margin: 0; line-height: 1.6; }
header, footer { padding: 1.25rem; background: #f3f4f6; }
nav a { margin-right: 1rem; text-decoration: none; }
main { padding: 1.25rem; max-width: 900px; }