/* 源码精读成书样式。全部变量集中在 :root，换主色只改 --accent。 */

:root {
  --accent: #3f4a5a;
  --bg: #fbfaf8;
  --paper: #fff;
  --ink: #1c1f24;
  --sub: #5b6270;
  --faint: #8b93a1;
  --line: #e7e4de;
  --code-bg: #f7f6f3;
  --code-ink: #2b3038;
  --mark: rgba(63, 74, 90, .1);
  --shadow: 0 1px 2px rgba(28, 31, 36, .04), 0 8px 28px rgba(28, 31, 36, .05);
  --serif: "Songti SC", "Source Han Serif SC", "Noto Serif CJK SC", Georgia, serif;
  --sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Noto Sans CJK SC",
          "Microsoft YaHei", system-ui, sans-serif;
  --mono: "SF Mono", ui-monospace, Menlo, Consolas, "Liberation Mono", monospace;
  --measure: 40rem;
}

body.dark {
  --bg: #14161a;
  --paper: #191c21;
  --ink: #e6e6e4;
  --sub: #a6adb9;
  --faint: #767e8c;
  --line: #2a2e35;
  --code-bg: #1e2127;
  --code-ink: #d7dae0;
  --mark: rgba(150, 172, 205, .16);
  --shadow: 0 1px 2px rgba(0, 0, 0, .3), 0 10px 30px rgba(0, 0, 0, .28);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 76px; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.95;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a { color: inherit; }

/* ── 顶部阅读进度 ───────────────────────────── */

.progress {
  position: fixed; inset: 0 0 auto 0; height: 2px; z-index: 60;
  background: transparent; pointer-events: none;
}
.progress i {
  display: block; height: 100%; width: 0;
  background: var(--accent); transition: width .12s linear;
}

/* ── 封面 ──────────────────────────────────── */

.is-cover { background:
  radial-gradient(1100px 620px at 50% -8%, var(--mark), transparent 62%), var(--bg); }

.cover { max-width: 62rem; margin: 0 auto; padding: 0 24px 80px; }

.cover-hero {
  min-height: 92vh; display: flex; flex-direction: column;
  align-items: center; justify-content: center; text-align: center; gap: 4px;
}
.cover-hero .kicker {
  margin: 0 0 14px; font-size: 13px; letter-spacing: .34em; text-indent: .34em;
  color: var(--faint); text-transform: uppercase;
  animation: rise .8s .05s both;
}
.cover-hero h1 {
  margin: 0; font-family: var(--serif); font-weight: 700;
  font-size: clamp(2.2rem, 6vw, 4rem); line-height: 1.28; letter-spacing: -.01em;
  max-width: 22ch; animation: rise .9s .12s both;
}
.cover-hero .sub {
  margin: 20px 0 0; max-width: 34rem; color: var(--sub); font-size: 1.02rem;
  line-height: 1.85; animation: rise .9s .2s both;
}
.cover-hero .by {
  margin: 26px 0 0; font-size: 14px; color: var(--faint); letter-spacing: .08em;
  animation: rise .9s .28s both;
}

.stats { display: flex; gap: 40px; margin: 40px 0 0; animation: rise .9s .36s both; }
.stat { display: flex; flex-direction: column; align-items: center; }
.stat b {
  font-family: var(--serif); font-size: 2rem; font-weight: 700;
  font-variant-numeric: tabular-nums; line-height: 1.2;
}
.stat span { font-size: 12px; color: var(--faint); letter-spacing: .1em; }

.cover-hero .anchor {
  margin: 34px 0 0; font-family: var(--mono); font-size: 12px; color: var(--faint);
  animation: rise .9s .44s both;
}
.src-repo {
  margin-top: 6px; font-family: var(--mono); font-size: 12px;
  color: var(--accent); text-decoration: none; border-bottom: 1px solid transparent;
  animation: rise .9s .48s both;
}
.src-repo:hover { border-bottom-color: currentColor; }

.start {
  margin-top: 40px; padding: 13px 34px; border-radius: 999px;
  background: var(--accent); color: #fff; text-decoration: none;
  font-size: 15px; letter-spacing: .04em;
  box-shadow: var(--shadow); transition: transform .2s, box-shadow .2s;
  animation: rise .9s .56s both;
}
.start:hover { transform: translateY(-2px); box-shadow: 0 10px 30px rgba(28, 31, 36, .16); }

.cover-toc { padding: 20px 0 0; }
.cover-toc h2 {
  margin: 0 0 26px; font-family: var(--serif); font-size: 1.3rem; font-weight: 700;
  letter-spacing: .02em; text-align: center;
}
ol.toc { list-style: none; margin: 0; padding: 0; }
ol.toc li { border-top: 1px solid var(--line); }
ol.toc li:last-child { border-bottom: 1px solid var(--line); }
ol.toc a {
  display: grid; grid-template-columns: 3.4rem 1fr; gap: 2px 18px;
  padding: 20px 14px; text-decoration: none;
  transition: background .18s, padding-left .18s;
}
ol.toc a:hover { background: var(--paper); padding-left: 22px; }
ol.toc .n {
  grid-row: 1 / span 2; font-family: var(--serif); font-size: 1.5rem;
  color: var(--faint); font-variant-numeric: tabular-nums; line-height: 1.4;
}
ol.toc .t { font-size: 1.02rem; font-weight: 600; line-height: 1.6; }
ol.toc .d { font-size: 14px; color: var(--sub); line-height: 1.75; }

.colophon-link {
  display: inline-block; margin-top: 30px; font-size: 14px; color: var(--sub);
  text-decoration: none; border-bottom: 1px solid var(--line);
}
.colophon-link:hover { color: var(--accent); border-bottom-color: currentColor; }

/* ── 顶栏 ──────────────────────────────────── */

.topbar {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; gap: 16px;
  padding: 12px 24px; background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(1.4) blur(10px);
  border-bottom: 1px solid var(--line);
}
.topbar .home {
  font-size: 14px; font-weight: 600; text-decoration: none;
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}
.topbar .pos {
  margin-left: auto; font-family: var(--mono); font-size: 12px; color: var(--faint);
  font-variant-numeric: tabular-nums;
}
.topbar .theme {
  width: 30px; height: 30px; border-radius: 8px; cursor: pointer;
  border: 1px solid var(--line); background: transparent; color: var(--sub);
  display: grid; place-items: center;
}
.topbar .theme::before { content: "◐"; font-size: 15px; }
.topbar .theme:hover { border-color: var(--accent); color: var(--accent); }

/* ── 正文骨架 ──────────────────────────────── */

.wrap {
  display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, var(--measure)) minmax(0, 1fr);
  gap: 0 32px; max-width: 84rem; margin: 0 auto; padding: 0 24px;
}
.side { grid-column: 1; }
.side nav {
  position: sticky; top: 84px; padding: 44px 0 40px;
  max-height: calc(100vh - 96px); overflow-y: auto;
  display: flex; flex-direction: column; gap: 2px;
  border-right: 1px solid var(--line); margin-right: 8px;
}
.side a {
  padding: 5px 14px 5px 12px; font-size: 13px; line-height: 1.6;
  color: var(--faint); text-decoration: none;
  border-left: 2px solid transparent; transition: color .16s, border-color .16s;
}
.side a.lv3 { padding-left: 26px; font-size: 12.5px; }
.side a:hover { color: var(--ink); }
.side a.on { color: var(--accent); border-left-color: var(--accent); font-weight: 600; }

.chapter { grid-column: 2; padding: 44px 0 88px; min-width: 0; }

.ch-num {
  margin: 0 0 10px; font-family: var(--mono); font-size: 12px;
  letter-spacing: .22em; color: var(--faint);
}
.chapter > h1 {
  margin: 0 0 20px; font-family: var(--serif); font-weight: 700;
  font-size: clamp(1.7rem, 3.6vw, 2.4rem); line-height: 1.36; letter-spacing: -.005em;
}
.ch-meta {
  display: flex; flex-direction: column; gap: 4px;
  margin: 0 0 52px; padding: 14px 18px; border-radius: 10px;
  background: var(--paper); border: 1px solid var(--line);
  font-family: var(--mono); font-size: 12px; line-height: 1.8; color: var(--sub);
}

/* ── 章节段落与标题 ────────────────────────── */

.chapter p { margin: 0 0 22px; }
.chapter p + p { margin-top: -4px; }

h2.sec {
  position: relative; margin: 72px 0 24px; padding-top: 26px;
  font-family: var(--serif); font-size: 1.42rem; font-weight: 700; line-height: 1.5;
  letter-spacing: .01em; border-top: 1px solid var(--line);
}
h2.sec .sec-mark {
  position: absolute; top: -1px; left: 0; width: 46px; height: 2px;
  background: var(--accent);
}
.chapter h3 {
  margin: 44px 0 16px; font-size: 1.08rem; font-weight: 700; line-height: 1.65;
  letter-spacing: .01em;
}
.chapter h4 { margin: 30px 0 12px; font-size: 1rem; font-weight: 600; }

.chapter ul, .chapter ol { margin: 0 0 22px; padding-left: 1.4em; }
.chapter li { margin: 0 0 9px; }
.chapter li > ul, .chapter li > ol { margin: 9px 0 4px; }

.chapter blockquote {
  margin: 0 0 24px; padding: 4px 0 4px 20px;
  border-left: 2px solid var(--accent);
  color: var(--sub); font-size: .97rem;
}
.chapter blockquote p:last-child { margin-bottom: 0; }

.chapter hr { margin: 44px 0; border: 0; border-top: 1px solid var(--line); }

.chapter strong { font-weight: 700; }
.chapter em { font-style: normal; background: var(--mark); padding: 0 .2em; border-radius: 3px; }

code {
  font-family: var(--mono); font-size: .875em;
  background: var(--code-bg); color: var(--code-ink);
  padding: .12em .38em; border-radius: 4px;
  word-break: break-word;
}

/* ── 表格 ──────────────────────────────────── */

.chapter table {
  width: 100%; margin: 0 0 26px; border-collapse: collapse;
  font-size: 14.5px; line-height: 1.75;
  background: var(--paper); border: 1px solid var(--line); border-radius: 10px;
  overflow: hidden; display: table;
}
.chapter th, .chapter td {
  padding: 11px 14px; text-align: left; vertical-align: top;
  border-bottom: 1px solid var(--line);
}
.chapter th { font-weight: 600; font-size: 13.5px; color: var(--sub); background: var(--code-bg); }
.chapter tr:last-child td { border-bottom: 0; }
.chapter td code { font-size: .84em; }

/* ── 源码引用块 ────────────────────────────── */

figure.cite, figure.code {
  margin: 0 0 26px; border: 1px solid var(--line); border-radius: 10px;
  background: var(--paper); overflow: hidden; box-shadow: var(--shadow);
}
.cite-head, .code-head {
  display: flex; align-items: center; gap: 12px;
  padding: 9px 14px; background: var(--code-bg); border-bottom: 1px solid var(--line);
  font-family: var(--mono); font-size: 11.5px; color: var(--sub);
}
.cite-path {
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap; direction: rtl;
  text-align: left; flex: 1 1 auto; min-width: 0;
}
.cite-lines { color: var(--faint); flex: 0 0 auto; }
.cite-tools { margin-left: auto; display: flex; gap: 6px; flex: 0 0 auto; }
.cite-btn {
  font: inherit; font-size: 11px; cursor: pointer; color: var(--sub);
  padding: 2px 9px; border-radius: 999px;
  border: 1px solid var(--line); background: var(--paper);
  transition: color .15s, border-color .15s;
}
.cite-btn:hover { color: var(--accent); border-color: var(--accent); }
.cite-btn.on { color: #fff; background: var(--accent); border-color: var(--accent); }

pre {
  margin: 0; padding: 14px 0; overflow-x: auto;
  font-family: var(--mono); font-size: 13px; line-height: 1.75;
  color: var(--code-ink);
}
pre code { background: none; padding: 0; font-size: inherit; }

.cite-body .cl { display: flex; padding: 0 14px; }
.cite-body .ln {
  flex: 0 0 3.4em; text-align: right; padding-right: 1.1em;
  color: var(--faint); user-select: none; font-variant-numeric: tabular-nums;
}
.cite-body .lt { white-space: pre; }
.cite-body .cl.gap { color: var(--faint); font-style: italic; }
.cite-body .cl.gap .lt { opacity: .7; }

/* 逐段步进：未命中的段落压暗，命中的段落上底色 */
figure.cite.stepping .cl { opacity: .28; transition: opacity .25s, background .25s; }
figure.cite.stepping .cl.hot { opacity: 1; background: var(--mark); }

/* ── 图 ────────────────────────────────────── */

figure.diagram {
  margin: 0 0 28px; padding: 22px 18px; border: 1px solid var(--line);
  border-radius: 10px; background: var(--paper); text-align: center;
  box-shadow: var(--shadow); overflow-x: auto;
}
figure.diagram .mermaid { font-family: var(--sans); }
figure.diagram svg { max-width: 100%; height: auto; }
figure.diagram.drawing svg .edgePath path,
figure.diagram.drawing svg .flowchart-link,
figure.diagram.drawing svg .messageLine0,
figure.diagram.drawing svg .messageLine1 {
  stroke-dasharray: 1000; stroke-dashoffset: 1000;
  animation: draw 1.1s ease forwards;
}
figure.diagram.drawing svg .node, figure.diagram.drawing svg .actor,
figure.diagram.drawing svg .label { animation: fade .7s .18s both; }

/* ── 章末导航 ──────────────────────────────── */

.ch-nav {
  display: flex; gap: 16px; margin-top: 76px; padding-top: 26px;
  border-top: 1px solid var(--line); font-size: 14px;
}
.ch-nav a {
  flex: 1 1 0; min-width: 0; padding: 16px 18px; border-radius: 10px;
  background: var(--paper); border: 1px solid var(--line);
  text-decoration: none; color: var(--sub); line-height: 1.6;
  transition: border-color .18s, color .18s, transform .18s;
}
.ch-nav a:hover { color: var(--ink); border-color: var(--accent); transform: translateY(-1px); }
.ch-nav .next { text-align: right; }

/* ── 封底 ──────────────────────────────────── */

.colophon { max-width: 46rem; margin: 0 auto; padding: 56px 24px 90px; }
.colophon h1 {
  margin: 0 0 18px; font-family: var(--serif); font-size: 2rem; font-weight: 700;
}
.colophon .lead { color: var(--sub); margin: 0 0 38px; }
.colophon h2 {
  margin: 48px 0 14px; font-family: var(--serif); font-size: 1.2rem; font-weight: 700;
}
.colophon p { margin: 0 0 18px; }
.stat-table {
  width: 100%; border-collapse: collapse; font-size: 14px;
  background: var(--paper); border: 1px solid var(--line); border-radius: 10px;
  overflow: hidden;
}
.stat-table th, .stat-table td {
  padding: 9px 12px; border-bottom: 1px solid var(--line); text-align: left;
}
.stat-table th { font-size: 12.5px; color: var(--sub); background: var(--code-bg); font-weight: 600; }
.stat-table td:nth-child(3), .stat-table td:nth-child(4), .stat-table td:nth-child(5),
.stat-table th:nth-child(3), .stat-table th:nth-child(4), .stat-table th:nth-child(5) {
  text-align: right; font-variant-numeric: tabular-nums;
}
.stat-table tfoot td { font-weight: 700; background: var(--code-bg); }
.anchor-list, .how-list { padding-left: 1.3em; }
.anchor-list li, .how-list li { margin-bottom: 8px; }
.method-link {
  display: inline-block; margin-top: 12px; padding: 11px 22px; border-radius: 999px;
  background: var(--accent); color: #fff; text-decoration: none; font-size: 14px;
  transition: transform .18s;
}
.method-link:hover { transform: translateY(-1px); }

/* ── 页脚：署名固定出现在每一页 ────────────── */

.book-foot {
  display: flex; flex-wrap: wrap; align-items: center; justify-content: center;
  gap: 6px 14px; padding: 30px 24px 42px;
  border-top: 1px solid var(--line);
  font-size: 12.5px; color: var(--faint); text-align: center;
}
.book-foot a { color: var(--sub); text-decoration: none; border-bottom: 1px solid var(--line); }
.book-foot a:hover { color: var(--accent); border-bottom-color: currentColor; }
.book-foot .foot-repo { font-family: var(--mono); font-size: 12px; }

/* ── 入场动效 ──────────────────────────────── */

.reveal { opacity: 0; transform: translateY(14px); }
.reveal.in { opacity: 1; transform: none; transition: opacity .6s ease, transform .6s ease; }

@keyframes rise { from { opacity: 0; transform: translateY(16px); } to { opacity: 1; transform: none; } }
@keyframes fade { from { opacity: 0; } to { opacity: 1; } }
@keyframes draw { to { stroke-dashoffset: 0; } }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
  .reveal { opacity: 1; transform: none; }
}

/* ── 窄屏 ──────────────────────────────────── */

@media (max-width: 1080px) {
  .wrap { grid-template-columns: minmax(0, 1fr); }
  .side { display: none; }
  .chapter { grid-column: 1; max-width: var(--measure); margin: 0 auto; }
}

@media (max-width: 720px) {
  body { font-size: 16px; line-height: 1.9; }
  .cover { padding: 0 18px 60px; }
  .stats { gap: 26px; }
  .stat b { font-size: 1.6rem; }
  ol.toc a { grid-template-columns: 2.6rem 1fr; gap: 2px 12px; padding: 16px 6px; }
  .chapter { padding: 32px 0 64px; }
  .wrap { padding: 0 18px; }
  pre { font-size: 12px; }
  .cite-body .ln { flex-basis: 2.8em; }
  .ch-nav { flex-direction: column; }
  .ch-nav .next { text-align: left; }
}

/* ── 打印 ──────────────────────────────────── */

@media print {
  .topbar, .side, .progress, .ch-nav, .start { display: none; }
  body { background: #fff; font-size: 11pt; }
  .wrap { display: block; max-width: none; padding: 0; }
  figure.cite, figure.code, figure.diagram, .chapter table { break-inside: avoid; }
  h2.sec { break-after: avoid; }
  .chapter { padding: 0; }
}