body {
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Yu Gothic", sans-serif;
  line-height: 1.8;
  max-width: 720px;
  margin: 0 auto;
  padding: 24px 20px 80px;
  color: #1a1a1a;
  background: #fff;
}
h1 { font-size: 1.5rem; margin-top: 0; }
h2 { font-size: 1.15rem; margin-top: 2em; }
a { color: #0057B8; }
footer { margin-top: 3em; font-size: 0.85rem; color: #666; }

@media (prefers-color-scheme: dark) {
  body { background: #121212; color: #eaeaea; }
  a { color: #6cabdd; }
  footer { color: #999; }
}