:root {
  --accent: #ff9900;
  --navy: #232f3e;
  --text: #1f2933;
  --muted: #6b7280;
  --bg: #f7f7f8;
  --card: #ffffff;
}
@media (prefers-color-scheme: dark) {
  :root {
    --text: #e5e7eb;
    --muted: #9ca3af;
    --bg: #101418;
    --card: #1a2028;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Yu Gothic UI", "Noto Sans JP", sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.9;
}
header {
  background: var(--navy);
  color: #fff;
  padding: 28px 20px;
}
header .inner, main {
  max-width: 760px;
  margin: 0 auto;
}
header h1 { margin: 0; font-size: 1.35rem; }
header p { margin: 6px 0 0; font-size: 0.85rem; opacity: 0.75; }
header a { color: var(--accent); text-decoration: none; }
main { padding: 32px 20px 64px; }
.card {
  background: var(--card);
  border-radius: 16px;
  padding: 28px;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.06);
}
h2 {
  font-size: 1.05rem;
  border-left: 4px solid var(--accent);
  padding-left: 10px;
  margin: 32px 0 8px;
}
h2:first-child { margin-top: 0; }
p, li { font-size: 0.95rem; }
.updated { color: var(--muted); font-size: 0.8rem; }
footer {
  text-align: center;
  color: var(--muted);
  font-size: 0.78rem;
  padding: 0 20px 40px;
}
.nav { margin-top: 20px; font-size: 0.9rem; }
.nav a { color: var(--accent); text-decoration: none; margin-right: 16px; }
.nav a:hover { text-decoration: underline; }