:root {
  --bg: #ffffff; --fg: #111827; --muted: #4b5563; --line: #e5e7eb; --accent: #0f766e; --card: #f8fafc;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #0f172a; --fg: #f1f5f9; --muted: #94a3b8; --line: #334155; --accent: #5eead4; --card: #1e293b; }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--bg); color: var(--fg); line-height: 1.8;
  font-family: "Hiragino Sans", "Noto Sans JP", "Yu Gothic", Meiryo, system-ui, sans-serif;
}
.wrap { max-width: 720px; margin: 0 auto; padding: 32px 20px 64px; }
header.site { border-bottom: 1px solid var(--line); }
header.site .wrap { padding-top: 16px; padding-bottom: 16px; display: flex; justify-content: space-between; align-items: center; gap: 12px; flex-wrap: wrap; }
header.site a.brand { font-weight: 800; font-size: 1.25rem; color: var(--fg); text-decoration: none; }
header.site nav a { margin-left: 16px; color: var(--muted); text-decoration: none; font-size: .95rem; }
header.site nav a:hover { color: var(--accent); }
h1 { font-size: 1.7rem; line-height: 1.35; margin: 8px 0 4px; }
h2 { font-size: 1.2rem; margin: 36px 0 8px; padding-top: 12px; border-top: 1px solid var(--line); }
p, li { margin: 8px 0; }
ul, ol { padding-left: 1.4em; }
a { color: var(--accent); }
.meta { color: var(--muted); font-size: .9rem; }
.card { background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 16px 18px; margin: 16px 0; }
.en { margin-top: 48px; padding-top: 8px; border-top: 3px solid var(--line); }
.en h2 { border-top: none; padding-top: 0; }
footer.site { border-top: 1px solid var(--line); color: var(--muted); font-size: .9rem; }
footer.site .wrap { padding-top: 20px; padding-bottom: 28px; }
code { background: var(--card); border: 1px solid var(--line); border-radius: 6px; padding: 1px 6px; font-size: .92em; }