:root { --w: 960px; }
* { box-sizing: border-box; }
body { margin: 0; font-family: system-ui, sans-serif; line-height: 1.6; }
header, main, footer { max-width: var(--w); margin: 0 auto; padding: 16px; }
header { background: #f5f5f5; border-bottom: 1px solid #e5e5e5; }
nav a { margin-right: 12px; text-decoration: none; color: #333; }
button { padding: 8px 14px; border: 1px solid #ddd; border-radius: 8px; cursor: pointer; }
button:hover { background: #f0f0f0; }