body { margin: 0; font: 16px/1.55 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif; color: #1d1f23; background: #f6f7f9; }
main, footer { max-width: 760px; margin: 0 auto; padding: 24px 16px; }
h1 { font-size: 28px; margin: 16px 0; }
h2 { font-size: 20px; margin-top: 28px; }
a { color: #1a5fd0; }
.button { display: inline-block; padding: 10px 18px; background: #1d1f23; color: #fff; border-radius: 8px; text-decoration: none; }
footer { color: #666; font-size: 14px; border-top: 1px solid #ddd; }
@media (prefers-color-scheme: dark) {
  body { color: #e6e6e6; background: #15171a; }
  a { color: #7fb0ff; }
  .button { background: #e6e6e6; color: #15171a; }
  footer { color: #999; border-color: #333; }
}