:root {
  --bg: #faf6ef;
  --fg: #2c2820;
  --accent: #8b4513;
  --muted: #7a7265;
  --rule: #d4c9a8;
  --card: #fffdf7;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1a1814;
    --fg: #d4c9a8;
    --accent: #c9a55c;
    --muted: #8a8270;
    --rule: #3a3428;
    --card: #242018;
  }
}

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: "Noto Serif SC", "Source Han Serif SC", "Songti SC", "SimSun", serif;
  font-size: 18px;
  line-height: 1.9;
}

.wrap {
  max-width: 720px;
  margin: 0 auto;
  padding: 40px 24px 80px;
}

/* 目录页 */
.book-title {
  text-align: center;
  font-size: 36px;
  font-weight: 700;
  margin: 40px 0 8px;
  letter-spacing: 4px;
  color: var(--accent);
}

.book-subtitle {
  text-align: center;
  font-size: 16px;
  color: var(--muted);
  margin-bottom: 40px;
  letter-spacing: 2px;
}

.synopsis {
  background: var(--card);
  border-left: 4px solid var(--accent);
  padding: 20px 24px;
  margin: 32px 0;
  font-size: 16px;
  line-height: 1.85;
  color: var(--fg);
  text-indent: 2em;
}

.toc-title {
  font-size: 22px;
  border-bottom: 2px solid var(--rule);
  padding-bottom: 12px;
  margin-top: 48px;
  margin-bottom: 24px;
  letter-spacing: 2px;
}

.book-total {
  text-align: center;
  color: var(--muted);
  font-size: 14px;
  margin: 8px 0 24px;
  letter-spacing: 1px;
}

.volume-block {
  margin: 40px 0 48px;
}

.volume-title {
  font-size: 20px;
  color: var(--accent);
  letter-spacing: 3px;
  border-bottom: 1px solid var(--rule);
  padding-bottom: 8px;
  margin: 0 0 8px;
}

.volume-desc {
  color: var(--muted);
  font-size: 14px;
  margin-bottom: 6px;
  text-indent: 2em;
}

.volume-meta {
  color: var(--muted);
  font-size: 13px;
  text-align: right;
  margin-bottom: 12px;
}

.toc-list {
  list-style: none;
  padding: 0;
}

.toc-item {
  padding: 16px 0;
  border-bottom: 1px dashed var(--rule);
}

.toc-item a {
  color: var(--fg);
  text-decoration: none;
  display: block;
}

.toc-item a:hover {
  color: var(--accent);
}

.toc-num {
  display: inline-block;
  width: 70px;
  color: var(--accent);
  font-weight: 700;
}

.toc-title-text {
  font-weight: 700;
  font-size: 19px;
}

.toc-summary {
  display: block;
  margin-top: 6px;
  margin-left: 70px;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.6;
}

.toc-meta {
  display: inline-block;
  margin-left: 70px;
  margin-top: 4px;
  color: var(--muted);
  font-size: 13px;
}

/* 章节页 */
.chapter-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 0;
  border-bottom: 1px solid var(--rule);
  font-size: 15px;
}

.chapter-nav.bottom {
  border-bottom: none;
  border-top: 1px solid var(--rule);
  margin-top: 48px;
}

.chapter-nav a {
  color: var(--accent);
  text-decoration: none;
  padding: 6px 12px;
}

.chapter-nav a:hover {
  text-decoration: underline;
}

.chapter-nav .disabled {
  color: var(--muted);
  cursor: default;
  padding: 6px 12px;
}

.chapter-title {
  text-align: center;
  font-size: 28px;
  font-weight: 700;
  margin: 48px 0 12px;
  letter-spacing: 3px;
  color: var(--accent);
}

.chapter-num {
  text-align: center;
  font-size: 14px;
  color: var(--muted);
  margin-bottom: 40px;
  letter-spacing: 2px;
}

.chapter-body p {
  text-indent: 2em;
  margin: 0 0 14px;
  text-align: justify;
}

.footer {
  text-align: center;
  color: var(--muted);
  font-size: 13px;
  margin-top: 60px;
  padding-top: 20px;
  border-top: 1px solid var(--rule);
}

/* 学术论文样式 */
.paper-body h1 { font-size: 22px; margin: 40px 0 12px; letter-spacing: 1px; color: var(--accent); }
.paper-body h2 { font-size: 20px; margin: 36px 0 10px; border-bottom: 1px solid var(--rule); padding-bottom: 6px; }
.paper-body h3 { font-size: 17px; margin: 24px 0 8px; color: var(--accent); }
.paper-body p  { text-indent: 2em; margin: 0 0 14px; text-align: justify; }
.paper-body blockquote { border-left: 3px solid var(--accent); padding: 8px 16px; margin: 20px 0; color: var(--muted); font-size: 15px; }
.paper-body hr { border: none; border-top: 1px solid var(--rule); margin: 32px 0; }
.paper-body strong { color: var(--fg); }