:root {
    --bg-color: #ffffff;
    --text-color: #2c3e50;
    --link-color: #27ae60;
    --font-stack: system-ui, -apple-system, sans-serif;
}
@media (prefers-color-scheme: dark) {
    :root { --bg-color: #1a1a1a; --text-color: #e0e0e0; --link-color: #2ecc71; }
}
body {
    background: var(--bg-color);
    color: var(--text-color);
    font-family: var(--font-stack);
    line-height: 1.6;
    margin: 0;
    padding: 20px;
    max-width: 800px;
    margin: auto;
}
header, footer { padding: 20px 0; border-bottom: 1px solid #ccc; }
footer { border-top: 1px solid #ccc; border-bottom: none; font-size: 0.9em; }
a { color: var(--link-color); }
nav a { padding: 10px; display: inline-block; min-height: 44px; }
input, button { padding: 12px; font-size: 16px; margin: 5px 0; display: block; width: 100%; box-sizing: border-box; }
@media (prefers-reduced-motion: reduce) { * { transition: none !important; } }