* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --cream: #F5F0E8;
  --prussian: #1B3B6B;
  --copper: #8B7355;
  --warm-white: #EFE8D8;
  --ink: #1A1A1A;
  --amber: #E07856;
  --accent: var(--copper);
}

html, body {
  background: var(--cream);
  color: var(--ink);
  font-family: 'Source Han Serif SC', 'Noto Serif SC', 'Songti SC', serif;
  font-size: 18px;
  line-height: 1.85;
}

.container {
  max-width: 720px;
  margin: 0 auto;
  padding: 4rem 2rem;
}

/* ── 顶栏 ── */
.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.7rem 1.5rem;
  background: var(--cream);
  border-bottom: 1px solid rgba(139,115,85,0.2);
  font-family: 'Inter', 'Noto Sans SC', sans-serif;
}
.topbar-left {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--prussian);
  letter-spacing: 0.02em;
}
.topbar-right {
  display: flex;
  gap: 0.5rem;
}
.theme-toggle {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.4rem 0.8rem;
  border: 1px solid var(--copper);
  border-radius: 4px;
  background: transparent;
  color: var(--prussian);
  font-size: 0.8rem;
  font-family: inherit;
  cursor: pointer;
  transition: background 0.2s, color 0.2s;
}
.theme-toggle:hover {
  background: var(--warm-white);
}
.theme-toggle .icon {
  font-size: 1rem;
  line-height: 1;
}
.theme-toggle .label {
  font-size: 0.75rem;
  letter-spacing: 0.05em;
}

/* ── 封面 ── */
.cover {
  background: var(--prussian);
  color: var(--cream);
  text-align: center;
  padding: 8rem 2rem;
  position: relative;
  overflow: hidden;
}
.cover h1 {
  font-size: 4rem;
  font-weight: 700;
  letter-spacing: 0.15em;
  margin-bottom: 1rem;
  color: var(--cream);
}
.cover .subtitle {
  font-style: italic;
  font-size: 1.25rem;
  color: var(--copper);
  letter-spacing: 0.1em;
  margin-bottom: 3rem;
}
.cover .author {
  font-size: 1.1rem;
  opacity: 0.9;
}
.cover .year {
  margin-top: 1rem;
  font-size: 1rem;
  letter-spacing: 0.5em;
  color: var(--copper);
}
.cover-deco {
  position: absolute;
  border: 2px solid var(--copper);
  opacity: 0.3;
}
.cover-deco-1 {
  width: 300px; height: 300px;
  border-radius: 50%;
  top: -100px; left: -100px;
}
.cover-deco-2 {
  width: 200px; height: 200px;
  top: -50px; right: -50px;
  border-color: var(--cream);
}

/* ── 正文 ── */
h1, h2, h3, h4 {
  color: var(--prussian);
  font-weight: 700;
  margin-top: 2rem;
  margin-bottom: 1rem;
}
h1 { font-size: 2rem; border-bottom: 2px solid var(--copper); padding-bottom: 0.5rem; }
h2 { font-size: 1.5rem; }
h3 { font-size: 1.25rem; color: var(--copper); }

p {
  text-indent: 2em;
  margin-bottom: 1em;
  text-align: justify;
}

blockquote {
  border-left: 3px solid var(--copper);
  padding: 0.75rem 1.5rem;
  margin: 1.5rem 0;
  font-style: italic;
  background: var(--warm-white);
  color: var(--prussian);
}

/* ── 目录 ── */
.toc-list {
  list-style: none;
  padding: 2rem 0;
}
.toc-list li {
  display: flex;
  align-items: baseline;
  padding: 0.5rem 0;
  border-bottom: 1px dotted var(--copper);
}
.toc-list li a {
  color: var(--prussian);
  text-decoration: none;
  flex: 1;
}
.toc-list li a:hover {
  color: var(--copper);
}
.toc-list .toc-num {
  color: var(--copper);
  font-weight: 700;
  margin-right: 1rem;
  min-width: 2rem;
}

/* ── 引用 ── */
sup a {
  color: var(--copper);
  text-decoration: none;
}
.references {
  font-size: 0.9rem;
  color: var(--copper);
}
.references h2 { color: var(--prussian); }
.references li {
  margin-bottom: 0.5rem;
  padding-left: 2em;
  text-indent: -2em;
}

/* ── 代码块 ── */
code, pre {
  font-family: 'JetBrains Mono', 'Consolas', monospace;
  font-size: 0.9em;
}
pre {
  background: var(--warm-white);
  border-left: 3px solid var(--copper);
  padding: 1rem;
  border-radius: 2px;
  overflow-x: auto;
}

/* ── 页脚 ── */
.footer {
  text-align: center;
  padding: 2rem 0;
  color: var(--copper);
  font-size: 0.9rem;
  border-top: 1px solid var(--copper);
}

/* ── 暗色模式 ── */
[data-theme="dark"] {
  --cream: #1a1a2e;
  --prussian: #e07856;
  --copper: #c9a87c;
  --warm-white: #16213e;
  --ink: #e8e0d4;
  --amber: #e07856;
  --accent: #e07856;
}

[data-theme="dark"] html,
[data-theme="dark"] body {
  background: #1a1a2e;
  color: #e8e0d4;
}

[data-theme="dark"] h1,
[data-theme="dark"] h2 {
  color: #e07856;
}

[data-theme="dark"] h1 {
  border-bottom-color: #e07856;
}

[data-theme="dark"] h3 {
  color: #c9a87c;
}

[data-theme="dark"] p,
[data-theme="dark"] li,
[data-theme="dark"] td,
[data-theme="dark"] th {
  color: #e8e0d4;
}

[data-theme="dark"] .toc-list li {
  border-bottom-color: rgba(201, 168, 124, 0.2);
}

[data-theme="dark"] .toc-list li a {
  color: #e8e0d4;
}

[data-theme="dark"] .toc-list .toc-num {
  color: #c9a87c;
}

[data-theme="dark"] blockquote {
  border-left-color: #e07856;
  background: #16213e;
  color: #e07856;
}

[data-theme="dark"] pre {
  background: #16213e;
  border-left-color: #e07856;
}

[data-theme="dark"] code {
  color: #e8e0d4;
}

[data-theme="dark"] .footer {
  color: #c9a87c;
  border-top-color: rgba(201, 168, 124, 0.3);
}

[data-theme="dark"] .references {
  color: #c9a87c;
}

[data-theme="dark"] .references h2 {
  color: #e07856;
}

[data-theme="dark"] table {
  border-color: rgba(201, 168, 124, 0.3);
}

[data-theme="dark"] th {
  background: rgba(224, 120, 86, 0.1);
  color: #e07856;
  border-bottom-color: rgba(224, 120, 86, 0.4);
}

[data-theme="dark"] td {
  border-bottom-color: rgba(201, 168, 124, 0.15);
}

[data-theme="dark"] tr.odd {
  background: rgba(22, 33, 62, 0.5);
}

[data-theme="dark"] tr.even {
  background: rgba(26, 26, 46, 0.5);
}

[data-theme="dark"] hr,
[data-theme="dark"] hr {
  border-color: rgba(201, 168, 124, 0.3);
}