:root {
  --bg: #fbfaf7;
  --fg: #26292e;
  --muted: #6b7078;
  --accent: #2f4a6b;
  --line: #e2dfd7;
  --card: #ffffff;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #17191d;
    --fg: #e6e4de;
    --muted: #9aa0a8;
    --accent: #8fb0d6;
    --line: #2d3036;
    --card: #1f2227;
  }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Noto Sans JP", Meiryo, sans-serif;
  line-height: 1.9;
  font-size: 16px;
}
header, main, footer {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 16px;
}
header { padding-top: 28px; padding-bottom: 12px; border-bottom: 1px solid var(--line); }
.site-name { font-size: 1.05rem; font-weight: 700; letter-spacing: .04em; margin: 0; }
.site-name a { color: var(--fg); text-decoration: none; }
nav { margin-top: 10px; display: flex; gap: 18px; flex-wrap: wrap; font-size: .92rem; }
nav a { color: var(--accent); text-decoration: none; padding: 4px 0; }
nav a[aria-current="page"] { font-weight: 700; border-bottom: 2px solid var(--accent); }
main { padding-top: 28px; padding-bottom: 40px; }
h1 { font-size: 1.5rem; line-height: 1.5; margin: 0 0 1rem; }
h2 { font-size: 1.15rem; margin: 2rem 0 .6rem; padding-left: .6rem; border-left: 4px solid var(--accent); }
p { margin: 0 0 1rem; }
a { color: var(--accent); }
.lead { color: var(--muted); }
.book {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 16px 18px;
  margin: 0 0 14px;
}
.book h3 { margin: 0 0 .3rem; font-size: 1.02rem; line-height: 1.6; }
.book p { margin: 0 0 .6rem; font-size: .95rem; }
.book .tag { display: inline-block; font-size: .78rem; color: var(--muted); border: 1px solid var(--line); border-radius: 4px; padding: 0 6px; margin-bottom: .4rem; }
.book .go { font-size: .92rem; }
.note {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 14px 18px;
  font-size: .93rem;
  color: var(--muted);
}
ol.order { padding-left: 1.3rem; margin: 0 0 1rem; }
ol.order li { margin-bottom: .3rem; }
footer { padding-top: 16px; padding-bottom: 32px; border-top: 1px solid var(--line); font-size: .85rem; color: var(--muted); }
footer p { margin: 0 0 .4rem; }

/* 書籍カードの表紙 */
.book { display: flex; gap: 18px; align-items: flex-start; }
.book .body { flex: 1; min-width: 0; }
.book .cover { flex: 0 0 110px; line-height: 0; }
.book .cover img { width: 110px; height: auto; aspect-ratio: 5 / 8; object-fit: cover; border: 1px solid var(--line); border-radius: 4px; background: var(--card); }
.book.no-cover .cover { display: none; }
@media (max-width: 480px) {
  .book .cover { flex-basis: 80px; }
  .book .cover img { width: 80px; }
}
.group { font-size: 1.05rem; margin: 1.6rem 0 .6rem; color: var(--muted); }