:root { color-scheme: light dark; }
* { box-sizing: border-box; }
body { margin: 0; font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif; line-height: 1.6; }
.container { max-width: 880px; margin: 0 auto; padding: 24px; }
h1, h2, h3 { line-height: 1.2; }
header nav a { text-decoration: none; margin-right: 8px; }
ul { padding-left: 20px; }
section { margin: 28px 0; }
footer { margin-top: 40px; font-size: 0.9em; opacity: 0.8; }