/* =============================================================
   DeepSeek-V4 架构深度剖析 — 排版借鉴 lintsinghua.github.io
   sans-serif 主体 / 三栏 / 左侧品牌+目录 / 右侧章节小目录
   ============================================================= */

:root {
  --bg: #fdfdfb;
  --bg-soft: #f6f8fc;
  --bg-elev: #ffffff;
  --sidebar-bg: #f6f4ef;
  --sidebar-line: #ebe8e0;
  --fg: #1f2532;
  --fg-2: #4a546c;
  --fg-3: #707a8e;
  --fg-mute: #a0a8b8;
  --line: #e4e9f1;
  --line-soft: #edf1f6;
  --rule: #d4dae5;
  --accent: #71a4e1;
  --accent-soft: #edf3fb;
  --accent-strong: #4f8acb;
  --accent-subtle: #f5f9fd;
  --warn: #71a4e1;
  --info: #71a4e1;
  --good: #71a4e1;
  --code-bg: #f3f6fb;
  --code-fg: #1f2532;
  --kbd-bg: #edf1f6;
  --shadow: 0 1px 0 rgba(30,50,90,0.04);

  --sans: "Inter", "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB",
          system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --serif: "Source Serif 4", "Source Serif Pro", "Noto Serif SC", Georgia, "Times New Roman", serif;
  --mono: "JetBrains Mono", "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;

  --side-w: 256px;
  --toc-w: 240px;
  --content-max: 760px;
  --gutter: 56px;
}

[data-theme="dark"] {
  --bg: #10151e;
  --bg-soft: #161c28;
  --bg-elev: #1a2130;
  --sidebar-bg: #1a1f29;
  --sidebar-line: #2a3142;
  --fg: #e8ecf3;
  --fg-2: #b9c2d4;
  --fg-3: #8a93a8;
  --fg-mute: #6b7388;
  --line: #232a3a;
  --line-soft: #1a2030;
  --rule: #2c344a;
  --accent: #8fbaea;
  --accent-soft: #1c2738;
  --accent-strong: #b6d3f1;
  --accent-subtle: #141d2a;
  --code-bg: #1a2030;
  --code-fg: #e8ecf3;
  --kbd-bg: #202838;
  --shadow: 0 1px 0 rgba(0,0,0,0.4);
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
html { scroll-behavior: smooth; scroll-padding-top: 24px; }

body {
  background: var(--bg);
  color: var(--fg);
  font-family: var(--sans);
  font-size: 15px;
  line-height: 1.78;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-strong); }

img, svg { max-width: 100%; }

::selection { background: var(--accent-soft); color: var(--accent-strong); }

/* ============= LAYOUT ============= */
.layout {
  display: grid;
  grid-template-columns: var(--side-w) minmax(0, 1fr) var(--toc-w);
  align-items: start;
  max-width: 1440px;
  margin: 0 auto;
  min-height: 100vh;
}

/* ============= LEFT SIDEBAR ============= */
.sidebar {
  position: sticky;
  top: 0;
  height: 100vh;
  padding: 24px 16px 16px 18px;
  background: var(--sidebar-bg);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  font-size: 13.5px;
}

.side-scroll {
  flex: 1 1 auto;
  min-height: 0;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 18px;
  scrollbar-width: none;
  -ms-overflow-style: none;
}
.side-scroll::-webkit-scrollbar { width: 0; height: 0; display: none; }

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 0 4px 14px;
  margin-bottom: 12px;
  border-bottom: 1px solid var(--line-soft);
  flex-shrink: 0;
}
.brand-logo {
  flex-shrink: 0;
  width: 36px;
  height: 36px;
  display: grid;
  place-items: center;
  border-radius: 9px;
  background: var(--accent-soft);
  color: var(--accent);
}
.brand-logo svg { width: 24px; height: 24px; display: block; }
.brand-meta { display: flex; flex-direction: column; gap: 4px; min-width: 0; }
.brand-title {
  font-size: 16px;
  font-weight: 700;
  letter-spacing: 0.2px;
  color: var(--fg);
  line-height: 1.3;
}
.brand-sub {
  font-size: 12px;
  color: var(--fg-3);
  line-height: 1.5;
}

.side-section { display: flex; flex-direction: column; }
.side-section-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding: 4px 8px;
  margin: 6px -8px 6px;
  border-radius: 6px;
  text-decoration: none;
  transition: background 0.12s, color 0.12s;
}
a.side-section-head { cursor: pointer; }
a.side-section-head:hover { background: var(--bg-soft); }
a.side-section-head:hover .side-title { color: var(--fg); }
a.side-section-head:hover .side-section-arrow { color: var(--accent); transform: translateX(2px); }
.side-section-head.active {
  background: var(--accent-soft);
}
.side-section-head.active .side-title {
  color: var(--accent-strong);
}
.side-title {
  font-size: 11.5px;
  font-weight: 600;
  letter-spacing: 0.6px;
  color: var(--fg-3);
  flex: 1 1 auto;
  min-width: 0;
  transition: color 0.12s;
}
.side-section-arrow {
  font-size: 14px;
  line-height: 1;
  color: var(--fg-mute);
  flex-shrink: 0;
  transition: color 0.12s, transform 0.12s;
}
.side-link {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 6px 8px;
  margin: 1px -8px;
  border-radius: 6px;
  color: var(--fg-2);
  font-size: 13.5px;
  line-height: 1.5;
  transition: background 0.12s, color 0.12s;
}
.side-link .num {
  display: inline-block;
  width: 18px;
  flex-shrink: 0;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--fg-mute);
  letter-spacing: 0.2px;
}
.side-link:hover { background: var(--bg-soft); color: var(--fg); }
.side-link.active {
  background: var(--accent-soft);
  color: var(--accent-strong);
  font-weight: 600;
}
.side-link.active .num { color: var(--accent); }

.side-bottom {
  flex-shrink: 0;
  padding: 14px 4px 0;
  margin-top: 8px;
  border-top: 1px solid var(--sidebar-line);
  background: transparent;
}
.side-controls {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}
.icon-btn {
  width: 34px; height: 34px;
  display: grid; place-items: center;
  border: 1px solid var(--line);
  background: var(--bg);
  color: var(--fg-2);
  border-radius: 999px;
  font-size: 14px;
  cursor: pointer;
  transition: all 0.15s;
}
.icon-btn:hover { color: var(--accent); border-color: var(--accent); }
.lang-btn {
  height: 34px;
  padding: 0 12px;
  display: inline-flex; align-items: center;
  border: 1px solid var(--line);
  border-radius: 999px;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.4px;
  color: var(--fg-2);
}
.lang-btn:hover { color: var(--accent); border-color: var(--accent); }
.gh-btn {
  height: 34px;
  padding: 0 12px;
  display: inline-flex; align-items: center; gap: 6px;
  border: 1px solid var(--line);
  border-radius: 999px;
  font-size: 12.5px;
  font-weight: 600;
  color: var(--fg-2);
}
.gh-btn svg { width: 14px; height: 14px; }
.gh-btn:hover { color: var(--accent); border-color: var(--accent); }

.side-foot {
  font-size: 11.5px;
  font-weight: 600;
  letter-spacing: 0.4px;
  color: var(--fg-mute);
  line-height: 1.4;
  margin-top: 8px;
}

/* ============= MAIN ============= */
.content {
  padding: 56px var(--gutter) 160px;
  max-width: 100%;
  min-width: 0;
}
.content-inner {
  max-width: var(--content-max);
  margin: 0 auto;
}

/* ============= TYPOGRAPHY ============= */
.eyebrow {
  display: inline-block;
  color: var(--accent);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.4px;
  margin-bottom: 16px;
}
h1.page-title {
  font-family: var(--sans);
  font-size: 40px;
  font-weight: 700;
  letter-spacing: -0.4px;
  line-height: 1.25;
  margin: 0 0 18px;
  color: var(--fg);
}
h2 {
  font-size: 26px;
  font-weight: 700;
  letter-spacing: -0.2px;
  line-height: 1.35;
  margin: 56px 0 16px;
  color: var(--fg);
  scroll-margin-top: 24px;
}
h3 {
  font-size: 19px;
  font-weight: 700;
  line-height: 1.4;
  margin: 36px 0 12px;
  color: var(--fg);
  scroll-margin-top: 24px;
}
h4 {
  font-size: 15.5px;
  font-weight: 700;
  margin: 24px 0 10px;
  color: var(--fg);
  scroll-margin-top: 24px;
}
p { margin: 12px 0; color: var(--fg); }
.lead { font-size: 16px; color: var(--fg-2); }

strong { color: var(--fg); font-weight: 700; }
em { color: var(--fg-2); font-style: italic; }

ul, ol { padding-left: 22px; margin: 12px 0; }
li { margin: 6px 0; color: var(--fg); }
li::marker { color: var(--accent); }

hr {
  border: none;
  border-top: 1px solid var(--line);
  margin: 48px 0;
}

code {
  font-family: var(--mono);
  font-size: 0.88em;
  background: var(--code-bg);
  color: var(--code-fg);
  padding: 1px 6px;
  border-radius: 4px;
}
pre {
  font-family: var(--mono);
  background: var(--code-bg);
  color: var(--code-fg);
  padding: 14px 16px;
  border-radius: 8px;
  overflow-x: auto;
  font-size: 13px;
  line-height: 1.65;
  margin: 16px 0;
}
pre code { background: transparent; padding: 0; }

/* ============= COVER ============= */
.cover {
  padding: 12px 0 56px;
  border-bottom: 1px solid var(--line);
  margin-bottom: 8px;
}
.cover-logo {
  width: 88px;
  height: 88px;
  display: grid;
  place-items: center;
  border-radius: 20px;
  background: var(--accent-soft);
  color: var(--accent);
  margin-bottom: 28px;
}
.cover-logo svg { width: 56px; height: 56px; }
.cover-tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 12.5px;
  font-weight: 600;
  letter-spacing: 0.6px;
  color: var(--accent);
  text-transform: uppercase;
  margin-bottom: 14px;
}
.cover-title {
  font-size: 44px;
  font-weight: 700;
  letter-spacing: -0.6px;
  line-height: 1.2;
  margin: 0 0 18px;
  color: var(--fg);
}
.cover-sub {
  font-size: 17px;
  line-height: 1.7;
  color: var(--fg-2);
  margin: 0 0 28px;
  max-width: 640px;
}
.cover-stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  margin: 28px 0 28px;
}
.cover-stats .stat {
  padding: 18px 16px;
  border-right: 1px solid var(--line-soft);
}
.cover-stats .stat:nth-child(3n) { border-right: none; }
.cover-stats .stat:nth-child(n+4) { border-top: 1px solid var(--line-soft); }
.stat-num {
  font-size: 22px;
  font-weight: 700;
  letter-spacing: -0.2px;
  color: var(--fg);
  line-height: 1.2;
  display: block;
}
.stat-lab {
  font-size: 12px;
  color: var(--fg-3);
  margin-top: 4px;
  display: block;
}
.cover-cta {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 8px;
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 16px;
  font-size: 13.5px;
  font-weight: 600;
  border-radius: 8px;
  border: 1px solid var(--line);
  color: var(--fg);
  background: var(--bg);
  transition: all 0.15s;
  cursor: pointer;
}
.btn:hover { border-color: var(--accent); color: var(--accent); }
.btn-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}
.btn-primary:hover { background: var(--accent-strong); border-color: var(--accent-strong); color: #fff; }

.release-card {
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--bg-2, var(--accent-soft));
  padding: 22px 24px;
  margin: 8px 0 28px;
}
.release-card-tag {
  display: inline-block;
  font-size: 11.5px;
  font-weight: 700;
  letter-spacing: 0.8px;
  color: var(--accent);
  text-transform: uppercase;
  margin-bottom: 8px;
}
.release-card-title {
  font-size: 19px;
  font-weight: 700;
  margin: 0 0 10px;
  color: var(--fg);
}
.release-card p {
  font-size: 14.5px;
  line-height: 1.75;
  color: var(--fg-2);
  margin: 0 0 10px;
}
.release-card ul {
  margin: 8px 0 14px;
  padding-left: 22px;
  font-size: 14px;
  line-height: 1.75;
  color: var(--fg-2);
}
.release-card ul li { margin: 4px 0; }
.release-card-links {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: 14px;
}

/* ============= CHAPTER ============= */
.chapter { padding: 56px 0; border-top: 1px solid var(--line-soft); scroll-margin-top: 24px; }
.chapter:first-of-type { border-top: none; }
.chapter-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--accent);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.4px;
  margin-bottom: 14px;
}
.chapter-eyebrow .dot { width: 4px; height: 4px; border-radius: 999px; background: var(--accent); }
.chapter-title {
  font-family: var(--serif);
  font-size: 32px;
  font-weight: 700;
  letter-spacing: -0.3px;
  line-height: 1.25;
  margin: 0 0 14px;
  color: var(--fg);
}
.chapter-sub {
  font-size: 15px;
  color: var(--fg-2);
  margin: 0 0 32px;
  line-height: 1.7;
}
.chapter h3, .chapter h4,
.page-body h3, .page-body h4 {
  font-family: var(--serif);
}

/* ============= CALLOUT ============= */
.callout {
  border: none;
  border-left: 3px solid var(--accent);
  background: transparent;
  padding: 4px 0 4px 18px;
  border-radius: 0;
  margin: 20px 0;
  font-size: 14.5px;
}
.callout-title {
  font-weight: 700;
  font-size: 13px;
  color: var(--fg);
  margin-bottom: 6px;
  letter-spacing: 0.2px;
}
.callout p { margin: 6px 0; }
.callout ul { margin: 6px 0; padding-left: 20px; }
.callout-info { border-left-color: var(--accent); }
.callout-warn { border-left-color: var(--accent-strong); }
.callout-good { border-left-color: var(--accent); }
.callout-quote {
  border-left-width: 3px;
  font-style: italic;
  color: var(--fg-2);
}

/* ============= GRID CARDS ============= */
.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin: 18px 0;
}
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  margin: 18px 0;
}
.card {
  display: block;
  padding: 16px 18px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--bg);
  color: var(--fg);
  transition: border-color 0.15s, background 0.15s;
}
.card:hover { border-color: var(--accent); background: var(--bg-soft); color: var(--fg); }
.card-tag {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.3px;
  color: var(--accent);
  margin-bottom: 6px;
}
.card h4 { margin: 4px 0 6px; font-size: 14.5px; }
.card p { margin: 0; font-size: 13px; color: var(--fg-2); line-height: 1.6; }

.mini-card {
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--bg-soft);
}
.mini-num {
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 4px;
}
.mini-card h4 { margin: 0 0 4px; font-size: 14px; }
.mini-card p { margin: 0; font-size: 12.5px; color: var(--fg-2); line-height: 1.55; }

/* ============= TABLE ============= */
.config-table { margin: 18px 0; overflow-x: auto; }
.config-table table {
  width: 100%;
  border-collapse: collapse;
  font-size: 13.5px;
}
.config-table th {
  text-align: left;
  padding: 10px 12px;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.3px;
  color: var(--fg-3);
  text-transform: uppercase;
  border-bottom: 1px solid var(--line);
}
.config-table td {
  padding: 10px 12px;
  border-bottom: 1px solid var(--line-soft);
  color: var(--fg);
  vertical-align: top;
}
.config-table tr:last-child td { border-bottom: none; }

/* ============= MATH ============= */
.math-block {
  margin: 18px 0;
  font-size: 14.5px;
}
.math-block .katex-display { margin: 0; }

/* ============= ALGORITHM (LaTeX algorithm2e-like) ============= */
.algo {
  margin: 22px 0;
  padding: 0;
  border-top: 2px solid var(--fg);
  border-bottom: 2px solid var(--fg);
  background: var(--bg);
  font-family: var(--serif);
  font-size: 14.5px;
  line-height: 1.7;
  color: var(--fg);
}
.algo-title {
  padding: 8px 14px 6px;
  border-bottom: 1px solid var(--fg);
  font-family: var(--sans);
  font-weight: 700;
  font-size: 14px;
  letter-spacing: 0.2px;
}
.algo-inputs {
  padding: 8px 14px 4px;
  font-family: var(--sans);
  font-size: 13.5px;
  color: var(--fg-2);
}
.algo-inputs strong { color: var(--fg); }
.algo-body {
  list-style: none;
  margin: 4px 0 8px;
  padding: 0 14px 0 0;
  counter-reset: algo-line;
}
.algo-body > li {
  counter-increment: algo-line;
  position: relative;
  padding-left: 44px;
  min-height: 1.7em;
}
.algo-body > li::before {
  content: counter(algo-line) ":";
  position: absolute;
  left: 14px;
  width: 22px;
  text-align: right;
  font-family: var(--mono);
  font-size: 12.5px;
  color: var(--fg-3);
}
.algo-body .ind-1 { padding-left: 64px; }
.algo-body .ind-2 { padding-left: 84px; }
.algo-body .ind-3 { padding-left: 104px; }
.algo-body .ind-1::before,
.algo-body .ind-2::before,
.algo-body .ind-3::before { left: 14px; }
.algo-kw { font-weight: 700; }
.algo-cmt {
  color: var(--fg-3);
  font-style: italic;
  margin-left: 8px;
  font-size: 13px;
}
.algo .katex { font-size: 1em; }

/* ============= DIAGRAM ============= */
.diagram-wrap {
  /* 突破 760px 文本列限制，向两侧各扩 80px（内容列实际宽度由 .content 提供，
     content gutter 56px + 一些余量），让 LR 流程图多挣横向空间 */
  margin: 22px -80px;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--bg);
  overflow-x: auto;
  overflow-y: auto;
  max-height: 80vh;          /* 防止超长图把页面拉成一柱擎天 */
  cursor: zoom-in;
  position: relative;
}
.diagram-wrap .mermaid {
  display: inline-block;     /* inline 让 svg 自然宽度生效，容器横向滚动 */
  text-align: center;
  min-width: 100%;
}
.diagram-wrap .mermaid svg {
  max-width: none !important;  /* 强力覆盖 mermaid 内联样式，配合 useMaxWidth:false */
  height: auto !important;
}
.diagram-wrap::after {
  content: "🔍 点击放大";
  position: absolute;
  top: 8px; right: 14px;
  font-size: 11px;
  color: var(--fg-3);
  background: var(--bg);
  padding: 2px 8px;
  border-radius: 4px;
  border: 1px solid var(--line);
  pointer-events: none;
  opacity: 0.7;
}
/* 滚动条样式 */
.diagram-wrap::-webkit-scrollbar { height: 8px; width: 8px; }
.diagram-wrap::-webkit-scrollbar-track { background: var(--bg-soft); border-radius: 4px; }
.diagram-wrap::-webkit-scrollbar-thumb { background: var(--line); border-radius: 4px; }
.diagram-wrap::-webkit-scrollbar-thumb:hover { background: var(--rule); }

/* 全屏放大模式（点击触发，由 JS 加 .diagram-zoomed 类） */
.diagram-zoomed {
  position: fixed !important;
  inset: 5vh 5vw;
  z-index: 100;
  margin: 0 !important;
  max-height: 90vh;
  background: var(--bg-elev);
  box-shadow: 0 20px 60px rgba(0,0,0,0.25);
  cursor: zoom-out;
}
.diagram-zoomed::after {
  content: "✕ 点击或按 ESC 关闭";
}
.diagram-zoom-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(15,20,30,0.55);
  z-index: 99;
  cursor: zoom-out;
}

/* 移动端：放弃负 margin 破列，避免横向溢出全屏 */
@media (max-width: 1140px) {
  .diagram-wrap { margin: 22px 0; }
}
.caption {
  font-size: 12.5px;
  color: var(--fg-3);
  text-align: center;
  margin: -4px 0 18px;
  font-style: italic;
}

/* ============= RIGHT TOC ============= */
.toc {
  position: sticky;
  top: 0;
  height: 100vh;
  padding: 56px 20px 24px 18px;
  overflow-y: auto;
  font-size: 11.5px;
  scrollbar-width: none;
  -ms-overflow-style: none;
}
.toc::-webkit-scrollbar { width: 0; display: none; }
.toc-title {
  font-size: 11.5px;
  font-weight: 600;
  color: var(--fg-3);
  margin-bottom: 10px;
  letter-spacing: 0.4px;
  text-transform: uppercase;
}
.toc-list { list-style: none; padding: 0; margin: 0; }
.toc-list li { margin: 4px 0; }
.toc-list a {
  display: block;
  padding: 3px 0;
  color: var(--fg-3);
  font-size: 11.5px;
  line-height: 1.6;
  transition: color 0.12s;
}
.toc-list a:hover { color: var(--fg-2); }
.toc-list a.active { color: var(--accent-strong); font-weight: 600; }
.toc-list .lvl-3 { padding-left: 0; }
.toc-list .lvl-4 { padding-left: 12px; }

/* ============= MOBILE ============= */
.mobile-bar {
  display: none;
  position: sticky;
  top: 0;
  z-index: 30;
  background: var(--bg);
  border-bottom: 1px solid var(--line);
  padding: 10px 14px;
  align-items: center;
  gap: 10px;
}
.mobile-bar .hamburger {
  border: none;
  background: transparent;
  padding: 6px;
  cursor: pointer;
  color: var(--fg);
}
.mobile-bar .brand-mini {
  font-weight: 700;
  font-size: 14.5px;
  color: var(--fg);
}

@media (max-width: 1180px) {
  :root { --toc-w: 0px; }
  .layout { grid-template-columns: var(--side-w) minmax(0, 1fr); }
  .toc { display: none; }
}

@media (max-width: 860px) {
  :root { --side-w: 0px; --gutter: 24px; }
  .layout { grid-template-columns: minmax(0, 1fr); }
  body::before { display: none; }
  .sidebar {
    position: fixed;
    left: 0; top: 0;
    height: 100vh;
    width: 280px;
    z-index: 50;
    transform: translateX(-100%);
    transition: transform 0.25s ease;
    border-right: 1px solid var(--line);
    background: var(--sidebar-bg);
  }
  .layout.opened .sidebar { transform: translateX(0); }
  .mobile-bar { display: flex; }
  .content { padding: 24px 20px 100px; }
  .cover-title { font-size: 32px; }
  .cover-stats { grid-template-columns: repeat(2, 1fr); }
  .cover-stats .stat:nth-child(3n) { border-right: 1px solid var(--line-soft); }
  .cover-stats .stat:nth-child(2n) { border-right: none; }
  .grid-3 { grid-template-columns: 1fr; }
  .grid-2 { grid-template-columns: 1fr; }
  .chapter-title { font-size: 26px; }
  h2 { font-size: 22px; }
}

/* ============= MULTI-PAGE ADDITIONS ============= */
/* 部分概览页：顶部跳转条 + 上下半页分割线 */
.part-jump {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 20px 0 28px;
  padding: 12px 14px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--bg-soft);
}
.part-jump a {
  font-size: 13px;
  color: var(--fg-2);
  padding: 4px 10px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: var(--bg);
  text-decoration: none;
  transition: background 0.12s, color 0.12s, border-color 0.12s;
}
.part-jump a:hover {
  background: var(--accent-soft);
  color: var(--accent-strong);
  border-color: var(--accent-soft);
}
.part-divider {
  display: flex;
  align-items: center;
  gap: 14px;
  margin: 56px 0 32px;
  color: var(--fg-3);
  font-size: 12px;
  letter-spacing: 0.4px;
}
.part-divider::before,
.part-divider::after {
  content: "";
  flex: 1 1 auto;
  height: 1px;
  background: var(--line);
}
.part-divider span {
  flex-shrink: 0;
}

/* 上一节 / 下一节 */
.page-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  margin-top: 64px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
}
.page-nav-prev, .page-nav-next {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 6px 0 6px 14px;
  border: none;
  border-left: 2px solid var(--line);
  border-radius: 0;
  background: transparent;
  color: var(--fg);
  transition: border-left-color 0.12s, color 0.12s;
  min-height: 48px;
}
.page-nav-next {
  text-align: right;
  padding: 6px 14px 6px 0;
  border-left: none;
  border-right: 2px solid var(--line);
}
.page-nav-prev:hover, .page-nav-next:hover {
  background: transparent;
  color: var(--accent-strong);
}
.page-nav-prev:hover { border-left-color: var(--accent); }
.page-nav-next:hover { border-right-color: var(--accent); }
.page-nav-prev:hover .page-nav-title,
.page-nav-next:hover .page-nav-title { color: var(--accent-strong); }
.page-nav-empty {
  visibility: hidden;
}
.page-nav-label {
  font-size: 11.5px;
  color: var(--fg-3);
  letter-spacing: 0.3px;
  text-transform: uppercase;
}
.page-nav-title {
  font-size: 14.5px;
  font-weight: 600;
  color: var(--fg);
  line-height: 1.35;
}

/* 学习目标 / 小结 卡片 */
.objectives,
.recap {
  margin: 28px 0;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 22px 24px;
  background: var(--bg-elev);
  position: relative;
}
.objectives { border-left: 3px solid var(--accent); }
.recap     { border-left: 3px solid var(--accent-strong); }

.objectives-eyebrow,
.recap-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 1.2px;
  color: var(--accent-strong);
  text-transform: uppercase;
  margin-bottom: 6px;
}
.objectives h3,
.recap h3 {
  font-size: 18px;
  margin: 4px 0 12px;
}
.objectives ul,
.recap ul {
  margin: 0;
  padding-left: 22px;
}
.objectives li,
.recap li {
  margin: 6px 0;
}

/* 部分扉页：路线图卡片 */
.roadmap {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 12px;
  margin: 20px 0 8px;
}
.roadmap-card {
  display: block;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--bg-elev);
  color: var(--fg);
  transition: border-color 0.12s, background 0.12s;
}
.roadmap-card:hover {
  border-color: var(--accent);
  background: var(--accent-subtle);
  color: var(--fg);
}
.roadmap-num {
  font-size: 11px;
  font-weight: 700;
  color: var(--accent-strong);
  letter-spacing: 0.6px;
}
.roadmap-card h4 {
  margin: 4px 0 6px;
  font-size: 15.5px;
}
.roadmap-card p {
  margin: 0;
  font-size: 13px;
  color: var(--fg-2);
  line-height: 1.55;
}

/* 元信息行（前置知识/预计耗时） */
.meta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 16px 28px;
  margin: 10px 0 18px;
  font-size: 13px;
  color: var(--fg-2);
}
.meta-row strong {
  color: var(--fg);
  font-weight: 600;
  margin-right: 6px;
}

/* 自检题 / 互动占位（结构先建，等用户指点后填具体交互） */
.interactive-slot {
  margin: 24px 0;
  padding: 16px 18px;
  border: 1px dashed var(--rule);
  border-radius: 10px;
  background: var(--accent-subtle);
  color: var(--fg-3);
  font-size: 13px;
  font-style: italic;
}
.interactive-slot::before {
  content: "⚙ 互动占位";
  display: block;
  font-style: normal;
  font-weight: 700;
  letter-spacing: 0.4px;
  color: var(--accent-strong);
  margin-bottom: 4px;
  font-size: 11.5px;
  text-transform: uppercase;
}

/* 名词速通卡（章首 "X 是什么"） */
.term-card {
  margin: 18px 0 24px;
  padding: 18px 20px;
  border: 1px solid var(--line);
  border-left: 3px solid var(--accent-strong);
  border-radius: 10px;
  background: var(--bg-elev);
}
.term-card .term-eyebrow {
  font-size: 11px;
  letter-spacing: 1.4px;
  text-transform: uppercase;
  color: var(--accent-strong);
  font-weight: 700;
  margin-bottom: 8px;
}
.term-card .term-name {
  font-family: var(--serif);
  font-size: 18px;
  font-weight: 700;
  color: var(--fg);
  margin: 0 0 6px;
}
.term-card dl { margin: 8px 0 0; }
.term-card dt {
  font-weight: 600;
  color: var(--fg);
  margin-top: 10px;
  font-size: 13.5px;
}
.term-card dd {
  margin: 2px 0 0;
  color: var(--fg-2);
  font-size: 13.5px;
  line-height: 1.7;
}
.term-card .term-tagline {
  margin-top: 14px;
  padding-top: 10px;
  border-top: 1px dashed var(--line-soft);
  font-size: 13.5px;
  color: var(--fg);
  font-weight: 500;
}

/* 数值演练块（公式之后举具体数字） */
.numex {
  margin: 14px 0;
  padding: 12px 14px 12px 16px;
  border-left: 3px solid var(--accent);
  background: var(--accent-subtle);
  border-radius: 0 8px 8px 0;
  font-size: 13.5px;
  line-height: 1.7;
  color: var(--fg-2);
}
.numex .numex-tag {
  display: inline-block;
  font-size: 11px;
  letter-spacing: 1px;
  font-weight: 700;
  color: var(--accent-strong);
  text-transform: uppercase;
  margin-right: 8px;
}

/* 真实论文图（替换 fig-placeholder 后用这个） */
.paper-fig {
  margin: 24px 0;
  padding: 0;
  text-align: center;
}
.paper-fig img {
  max-width: 100%;
  height: auto;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--bg-elev);
}
.paper-fig figcaption {
  display: block;
  margin: 10px auto 0;
  max-width: 720px;
  font-size: 12.5px;
  color: var(--fg-2);
  line-height: 1.7;
  font-style: normal;
  text-align: left;
}
.paper-fig figcaption .fig-source {
  display: inline;
  margin: 0;
  color: var(--fg-3);
  font-style: italic;
  font-size: 12px;
}

/* 论文图占位符 */
.fig-placeholder {
  margin: 22px 0;
  padding: 28px 20px;
  border: 1.5px dashed var(--accent);
  border-radius: 10px;
  background: var(--accent-subtle);
  text-align: center;
  font-size: 13px;
  color: var(--fg-2);
}
.fig-placeholder .fig-tag {
  display: inline-block;
  font-size: 10.5px;
  letter-spacing: 1.2px;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--accent-strong);
  background: var(--bg-elev);
  padding: 3px 8px;
  border-radius: 4px;
  margin-bottom: 10px;
}
.fig-placeholder .fig-want {
  font-family: var(--serif);
  font-size: 14.5px;
  color: var(--fg);
  margin: 0 0 6px;
  font-weight: 600;
}
.fig-placeholder .fig-source {
  font-size: 12px;
  color: var(--fg-3);
  margin-top: 8px;
  font-style: italic;
}

/* 交互组件容器（章内 SVG / Canvas demo） */
.viz {
  margin: 22px 0;
  padding: 18px 20px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--bg-elev);
}
.viz-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 12px;
}
.viz-title {
  font-family: var(--serif);
  font-weight: 700;
  font-size: 14.5px;
  color: var(--fg);
}
.viz-tag {
  font-size: 10.5px;
  letter-spacing: 1.2px;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--accent-strong);
}
.viz-controls {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 10px;
  font-size: 13px;
  color: var(--fg-2);
}
.viz-controls label {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}
.viz-controls input[type="range"] {
  vertical-align: middle;
}
.viz-controls .viz-btn {
  font-family: var(--mono);
  font-size: 12px;
  padding: 4px 12px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--bg);
  color: var(--fg);
  cursor: pointer;
  transition: border-color .15s, color .15s;
}
.viz-controls .viz-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
}
.viz-controls .viz-btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}
.viz-readout {
  font-family: var(--mono);
  font-size: 12.5px;
  color: var(--fg);
  background: var(--bg-soft);
  padding: 2px 8px;
  border-radius: 4px;
}
.viz svg { display: block; max-width: 100%; height: auto; }
.viz-caption {
  margin-top: 10px;
  font-size: 12.5px;
  color: var(--fg-3);
  line-height: 1.7;
  font-style: italic;
}

/* 自检题（折叠答案） */
.quiz {
  margin: 16px 0;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--bg-elev);
}
.quiz-q {
  font-weight: 600;
  color: var(--fg);
  margin: 0 0 6px;
}
.quiz details {
  margin-top: 8px;
  font-size: 13.5px;
  color: var(--fg-2);
}
.quiz summary {
  cursor: pointer;
  color: var(--accent-strong);
  font-weight: 600;
  font-size: 13px;
  list-style: none;
}
.quiz summary::-webkit-details-marker { display: none; }
.quiz summary::before { content: "▸ "; }
.quiz details[open] summary::before { content: "▾ "; }

/* 章节顶部 breadcrumb */
.crumb {
  font-size: 12px;
  color: var(--fg-3);
  margin-bottom: 10px;
  letter-spacing: 0.4px;
}
.crumb a { color: var(--fg-3); }
.crumb a:hover { color: var(--accent-strong); }
.crumb .sep { margin: 0 8px; color: var(--fg-mute); }

@media (max-width: 600px) {
  .page-nav { grid-template-columns: 1fr; }
}

/* =============================================================
   专有名词悬浮释义 (Glossary tooltip)
   术语本身仅做下划线提示；气泡是单一全局元素 .gloss-tip
   挂在 <body> 上，通过 JS 计算 fixed 定位，
   绕开任何祖先元素的 overflow 裁剪（比如 .config-table）。
   ============================================================= */
.gloss {
  border-bottom: 1px dotted var(--accent);
  cursor: help;
  outline: none;
  transition: color 0.12s ease, border-color 0.12s ease;
}
.gloss:hover,
.gloss:focus {
  color: var(--accent-strong);
  border-bottom-color: var(--accent-strong);
  border-bottom-style: solid;
}

.gloss-tip {
  position: fixed;
  top: 0;
  left: 0;
  background: var(--bg-elev);
  color: var(--fg);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 10px 14px;
  font-size: 12.5px;
  font-weight: 400;
  font-style: normal;
  line-height: 1.65;
  letter-spacing: 0.1px;
  max-width: 320px;
  white-space: normal;
  text-align: left;
  z-index: 9999;
  box-shadow: 0 8px 24px rgba(30, 50, 90, 0.12);
  pointer-events: none;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-4px);
  transition: opacity 0.12s ease, transform 0.12s ease, visibility 0.12s ease;
}
.gloss-tip.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
[data-theme="dark"] .gloss-tip {
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.55);
}
@media (max-width: 720px) {
  .gloss-tip {
    max-width: min(280px, calc(100vw - 24px));
    font-size: 12px;
    padding: 9px 12px;
  }
}