/* 编译原理讲义 · 视觉与布局。零外链：只用系统字体，无图片、无 CDN。 */
:root {
  color-scheme: light;
  --bg: #fbfaf6;
  --paper: #ffffff;
  --ink: #1b1c1a;
  --muted: #54564f;
  --line: #d8d5ca;
  --accent: #1f5c46;
  --accent-soft: #e7efe9;
  --chip: #f1eee6;
  --mark: #fbeec4;
  --focus: #0b5fa5;
  --ok: #17603d;
  --ok-bg: #e7f3ec;
  --bad: #8f2222;
  --bad-bg: #f8e9e7;
  --shadow: 0 10px 30px rgba(20, 24, 20, .08);
  --radius: 10px;
  --mono: ui-monospace, "Cascadia Mono", "Consolas", "Noto Sans Mono CJK SC", monospace;
  --sans: "Segoe UI", "Noto Sans CJK SC", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
}

html[data-theme="dark"] {
  color-scheme: dark;
  --bg: #14171a;
  --paper: #1c2024;
  --ink: #e9e7e0;
  --muted: #b4b1a7;
  --line: #34393e;
  --accent: #8fd0b0;
  --accent-soft: #21382e;
  --chip: #242a2e;
  --mark: #4a3f1a;
  --focus: #93d2ff;
  --ok: #8fd6ad;
  --ok-bg: #1d3226;
  --bad: #ffb3a8;
  --bad-bg: #3a2422;
  --shadow: 0 10px 30px rgba(0, 0, 0, .35);
}

@media (prefers-color-scheme: dark) {
  html:not([data-theme="light"]) {
    color-scheme: dark;
    --bg: #14171a;
    --paper: #1c2024;
    --ink: #e9e7e0;
    --muted: #b4b1a7;
    --line: #34393e;
    --accent: #8fd0b0;
    --accent-soft: #21382e;
    --chip: #242a2e;
    --mark: #4a3f1a;
    --focus: #93d2ff;
    --ok: #8fd6ad;
    --ok-bg: #1d3226;
    --bad: #ffb3a8;
    --bad-bg: #3a2422;
    --shadow: 0 10px 30px rgba(0, 0, 0, .35);
  }
}

*, *::before, *::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: clamp(16px, .95rem + .18vw, 17.5px);
  line-height: 1.75;
  overflow-wrap: break-word;
}

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

a { color: var(--accent); text-underline-offset: .2em; }
a:hover { text-decoration-thickness: 2px; }

:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 2px;
  border-radius: 4px;
}

.skip {
  position: absolute;
  left: 1rem;
  top: -100px;
  z-index: 100;
  background: var(--paper);
  color: var(--ink);
  border: 2px solid var(--accent);
  border-radius: 8px;
  padding: .6rem .9rem;
  min-height: 44px;
}
.skip:focus { top: .7rem; }

.sr-only {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0, 0, 0, 0);
  white-space: nowrap; border: 0;
}

/* ---------- 顶栏 ---------- */
.top {
  position: sticky;
  top: 0;
  z-index: 40;
  background: color-mix(in srgb, var(--bg) 92%, transparent);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}
.top-in {
  max-width: 1240px;
  margin: 0 auto;
  padding: .7rem 1.25rem;
  display: flex;
  align-items: center;
  gap: .9rem 1.2rem;
  flex-wrap: wrap;
}
.brand { min-width: 0; flex: 1 1 22rem; }
.brand h1 {
  margin: 0;
  font-size: clamp(1.05rem, .85rem + .8vw, 1.42rem);
  line-height: 1.35;
  letter-spacing: .01em;
}
.brand .sub {
  margin: .15rem 0 0;
  font-size: .78rem;
  color: var(--muted);
  line-height: 1.5;
}
.tools {
  display: flex;
  align-items: center;
  gap: .5rem;
  flex-wrap: wrap;
  margin-left: auto;
}

button, .btn {
  font: inherit;
  font-size: .86rem;
  min-height: 44px;
  padding: .45rem .8rem;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: var(--paper);
  color: var(--ink);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: .35rem;
}
button:hover, .btn:hover { border-color: var(--accent); color: var(--accent); }
button:disabled { opacity: .5; cursor: not-allowed; }
button.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--paper);
  font-weight: 600;
}
html[data-theme="dark"] button.primary { color: #10171a; }
@media (prefers-color-scheme: dark) {
  html:not([data-theme="light"]) button.primary { color: #10171a; }
}
button.ghost { background: transparent; }
button[aria-pressed="true"] { border-color: var(--accent); background: var(--accent-soft); color: var(--accent); }

/* 检索 */
.search { position: relative; }
.search label { display: block; font-size: .76rem; color: var(--muted); margin-bottom: .15rem; }
.search input[type="search"] {
  font: inherit;
  font-size: .9rem;
  width: min(22rem, 72vw);
  min-height: 44px;
  padding: .5rem .7rem;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--paper);
  color: var(--ink);
}
.search input[type="search"]:focus { border-color: var(--accent); }
.search-results {
  position: absolute;
  z-index: 50;
  top: calc(100% + .35rem);
  left: 0;
  width: min(34rem, 92vw);
  max-height: 24rem;
  overflow: auto;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: .35rem;
}
.search-results[hidden] { display: none; }
.search-results ul { list-style: none; margin: 0; padding: 0; }
.search-results li + li { border-top: 1px solid var(--line); }
.search-results a {
  display: block;
  padding: .55rem .65rem;
  min-height: 44px;
  text-decoration: none;
  color: var(--ink);
  border-radius: 6px;
}
.search-results a:hover { background: var(--chip); }
.sr-title { display: block; font-weight: 600; font-size: .88rem; color: var(--accent); }
.sr-snip { display: block; font-size: .78rem; color: var(--muted); line-height: 1.5; }
.sr-empty { padding: .7rem; font-size: .85rem; color: var(--muted); }

/* ---------- 布局 ---------- */
.layout {
  max-width: 1240px;
  margin: 0 auto;
  padding: 1.6rem 1.25rem 4rem;
  display: grid;
  grid-template-columns: 268px minmax(0, 1fr);
  gap: 2.2rem;
  align-items: start;
}
.side {
  position: sticky;
  top: 6.5rem;
  max-height: calc(100vh - 8rem);
  overflow: auto;
  padding-right: .35rem;
  border-right: 1px solid var(--line);
}
.toc-h {
  font-size: .76rem;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 .4rem .5rem;
}
.toc ol { list-style: none; padding: 0; margin: 0 0 1rem; }
.toc > ol > li { margin: .2rem 0; }
.toc a {
  display: block;
  padding: .38rem .45rem;
  min-height: 38px;
  border-radius: 6px;
  color: var(--ink);
  text-decoration: none;
  font-size: .86rem;
  line-height: 1.4;
}
.toc a:hover { background: var(--chip); }
.toc a.active { background: var(--accent-soft); color: var(--accent); font-weight: 600; }
.toc .ch-link { font-weight: 700; font-size: .9rem; }
.toc .sub-q { padding-left: .9rem; }
.toc .sub-q a { color: var(--muted); font-size: .8rem; }
.toc .dim { opacity: .45; }
.toc-tools { display: none; }
.menu-btn { display: none; }

@media (max-width: 980px) {
  .layout { grid-template-columns: minmax(0, 1fr); padding: 1rem .9rem 2.5rem; gap: 1rem; }
  .side {
    position: static;
    max-height: none;
    border-right: 0;
    border-bottom: 1px solid var(--line);
    padding: 0 0 .8rem;
  }
  .side.is-collapsed { display: none; }
  .menu-btn { display: inline-flex; }
  .toc { max-height: 55vh; overflow: auto; }
  .search input[type="search"] { width: min(22rem, 78vw); }
  .tools { width: 100%; margin-left: 0; }
}

main { min-width: 0; }

/* ---------- 正文 ---------- */
.lede {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1.1rem 1.2rem;
  margin-bottom: 2rem;
}
.lede h2 { margin: 0 0 .55rem; font-size: 1.02rem; }
.lede p { margin: .45rem 0; font-size: .92rem; }
.lede dl { margin: .6rem 0 0; display: grid; grid-template-columns: 7.2rem minmax(0, 1fr); gap: .4rem .8rem; font-size: .86rem; }
.lede dt { font-weight: 600; color: var(--accent); }
.lede dd { margin: 0; }
@media (max-width: 520px) {
  .lede dl { grid-template-columns: minmax(0, 1fr); }
  .lede dt { margin-top: .5rem; }
}

.chapter { margin-bottom: 3.2rem; }
.chapter-head {
  border-top: 3px solid var(--accent);
  padding-top: 1rem;
  margin-bottom: 1rem;
}
.chapter-head h2 {
  margin: 0;
  font-size: clamp(1.35rem, 1.1rem + 1.1vw, 1.8rem);
  letter-spacing: .01em;
}
.chapter-head .ch-intro { margin: .5rem 0 0; color: var(--muted); font-size: .93rem; }

article.sec {
  border-top: 1px solid var(--line);
  padding-top: 1.5rem;
  margin-top: 2.2rem;
  scroll-margin-top: 6.5rem;
}
article.sec h3 {
  margin: 0 0 .15rem;
  font-size: clamp(1.1rem, .98rem + .5vw, 1.32rem);
  line-height: 1.45;
}
.sec-meta {
  margin: 0 0 .8rem;
  font-size: .76rem;
  color: var(--muted);
  letter-spacing: .02em;
}
.sec-src {
  margin: 1.1rem 0 0;
  padding-top: .6rem;
  border-top: 1px dashed var(--line);
  font-size: .78rem;
  color: var(--muted);
}
p { margin: .65rem 0; }
.body ul, .body ol { padding-left: 1.35rem; }
.body li { margin: .3rem 0; }

code {
  font-family: var(--mono);
  font-size: .9em;
  background: var(--chip);
  padding: .08rem .28rem;
  border-radius: 4px;
  overflow-wrap: anywhere;
}
pre.code {
  font-family: var(--mono);
  font-size: .84rem;
  line-height: 1.65;
  background: var(--chip);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: .8rem .9rem;
  overflow-x: auto;
  margin: .6rem 0 1rem;
  tab-size: 4;
}
pre.code code { background: none; padding: 0; font-size: 1em; }
figure.codefig { margin: 1.1rem 0; }
figure.codefig figcaption { font-size: .82rem; color: var(--muted); }

/* 概念卡 */
.concept {
  border: 1px solid var(--line);
  border-left: 4px solid var(--accent);
  border-radius: var(--radius);
  background: var(--paper);
  padding: 1rem 1.1rem;
  margin: 1rem 0 1.4rem;
}
.concept-head { display: flex; align-items: baseline; gap: .55rem; flex-wrap: wrap; }
.badge {
  flex: none;
  font-size: .7rem;
  font-weight: 700;
  letter-spacing: .04em;
  color: var(--accent);
  background: var(--accent-soft);
  border: 1px solid var(--accent);
  border-radius: 999px;
  padding: .1rem .45rem;
}
.concept-name { margin: 0; font-weight: 700; font-size: .98rem; }
.chain { list-style: none; counter-reset: step; padding: 0; margin: .75rem 0 0; }
.chain > li {
  counter-increment: step;
  position: relative;
  padding-left: 1.95rem;
  margin: .55rem 0;
  font-size: .92rem;
}
.chain > li::before {
  content: counter(step);
  position: absolute;
  left: 0; top: .2rem;
  width: 1.35rem; height: 1.35rem;
  display: grid; place-items: center;
  background: var(--chip);
  color: var(--muted);
  border-radius: 50%;
  font-size: .7rem;
  font-variant-numeric: tabular-nums;
}
.chain > li > b { display: block; font-size: .76rem; letter-spacing: .05em; color: var(--accent); margin-bottom: .1rem; }
.chain p { margin: .1rem 0; }
.chain ul { margin: .15rem 0; padding-left: 1.1rem; }
.reps { margin: .2rem 0 0; padding-left: 1.05rem; }
.reps > li { margin: .35rem 0; }
.reps b { font-size: .86rem; }

/* 表格 */
.tw {
  margin: 1rem 0 1.2rem;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--paper);
  overflow-x: auto;
}
.tw table { width: 100%; border-collapse: collapse; font-size: .88rem; }
.tw caption {
  caption-side: top;
  text-align: left;
  padding: .6rem .75rem;
  font-size: .82rem;
  color: var(--muted);
  border-bottom: 1px solid var(--line);
}
.tw th, .tw td {
  padding: .48rem .6rem;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
  line-height: 1.6;
}
.tw th { background: var(--chip); font-weight: 600; font-size: .8rem; letter-spacing: .02em; }
.tw tr:last-child td { border-bottom: 0; }
.tw .tnote {
  font-size: .78rem;
  color: var(--muted);
  padding: .55rem .75rem;
  border-top: 1px dashed var(--line);
  margin: 0;
}
.tw td:first-child { white-space: nowrap; }
@media (max-width: 480px) {
  .tw table { font-size: .82rem; }
  .tw th, .tw td { padding: .42rem .45rem; }
  .tw td:first-child { white-space: normal; }
}

/* 提示块 */
.note {
  border: 1px solid var(--line);
  border-left: 3px solid var(--muted);
  border-radius: 0 8px 8px 0;
  background: var(--paper);
  padding: .65rem .8rem;
  margin: 1rem 0;
  font-size: .88rem;
}
.note h4 { margin: 0 0 .25rem; font-size: .78rem; letter-spacing: .05em; color: var(--muted); }
.note p { margin: .2rem 0; }
.note.k-infer { border-left-style: dotted; }
.note.k-missing { border-left-style: dashed; }
.note.k-source { border-left-color: var(--accent); }
.note.k-out { border-left-color: var(--accent); background: var(--accent-soft); }

/* 树图 */
figure.tree {
  margin: 1.2rem 0;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--paper);
  padding: .9rem 1rem;
}
figure.tree svg { display: block; width: 100%; height: auto; max-width: 540px; margin: .3rem auto; }
figure.tree svg text { fill: var(--ink); font-family: var(--sans); }
figure.tree svg circle { stroke: var(--accent); fill: var(--paper); }
figure.tree svg line { stroke: var(--muted); }
figure.tree figcaption { font-size: .82rem; color: var(--muted); margin-bottom: .2rem; }
figure.tree .tnote { font-size: .8rem; color: var(--muted); margin: .3rem 0 0; }

/* ---------- 自测 ---------- */
.quiz {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--paper);
  padding: 1rem 1.1rem;
  margin: 1.4rem 0;
}
.quiz h4 { margin: 0 0 .6rem; font-size: .95rem; letter-spacing: .02em; }
.quiz-legend { margin: 0 0 .6rem; font-size: .78rem; color: var(--muted); }
.q { padding: .8rem 0; border-top: 1px dashed var(--line); }
.q:first-of-type { border-top: 0; padding-top: 0; }
.q-stem { margin: .1rem 0 .55rem; font-weight: 600; font-size: .93rem; }
.q-num { display: inline-block; color: var(--muted); font-weight: 400; font-size: .78rem; margin-right: .4rem; }
.q-type { font-size: .72rem; color: var(--accent); border: 1px solid var(--accent); border-radius: 4px; padding: 0 .25rem; margin-left: .35rem; font-weight: 600; }
.q-opts { list-style: none; margin: 0; padding: 0; display: grid; gap: .35rem; }
.q-opts li { margin: 0; }
.q-opts label {
  display: flex;
  gap: .55rem;
  align-items: flex-start;
  min-height: 44px;
  padding: .5rem .6rem;
  border: 1px solid var(--line);
  border-radius: 8px;
  cursor: pointer;
  font-size: .9rem;
  line-height: 1.6;
}
.q-opts label:hover { border-color: var(--accent); }
.q-opts input { flex: none; width: 1.05rem; height: 1.05rem; margin: .3rem 0 0; accent-color: var(--accent); }
.q-opts li.is-answer label { border-color: var(--ok); background: var(--ok-bg); }
.q-opts li.is-picked-wrong label { border-color: var(--bad); background: var(--bad-bg); }
.op-tag { font-size: .7rem; color: var(--ok); font-weight: 700; margin-left: auto; padding-left: .5rem; white-space: nowrap; }
.op-tag.wrong { color: var(--bad); }
.q-actions { display: flex; gap: .5rem; flex-wrap: wrap; margin-top: .6rem; }
.q-actions button { min-height: 40px; font-size: .84rem; }
.fb {
  margin-top: .6rem;
  padding: .55rem .7rem;
  border-left: 3px solid var(--muted);
  border-radius: 0 6px 6px 0;
  background: var(--chip);
  font-size: .87rem;
}
.fb.ok { border-left-color: var(--ok); background: var(--ok-bg); }
.fb.bad { border-left-color: var(--bad); background: var(--bad-bg); }
.fb .verdict { font-weight: 700; }
.fb .ref { color: var(--muted); }
.quiz-sum { margin: .9rem 0 0; font-size: .82rem; color: var(--muted); }

/* ---------- 演示 ---------- */
.demo {
  border: 1px solid var(--line);
  border-left: 4px solid var(--accent);
  border-radius: var(--radius);
  background: var(--paper);
  padding: 1rem 1.1rem;
  margin: 1.3rem 0;
}
.demo h4 { margin: 0 0 .2rem; font-size: .92rem; }
.demo-note { margin: 0 0 .7rem; font-size: .8rem; color: var(--muted); }
.demo-row { display: flex; gap: .5rem; flex-wrap: wrap; align-items: center; }
.demo input[type="text"] {
  font: inherit;
  font-family: var(--mono);
  letter-spacing: .08em;
  width: 11rem;
  max-width: 100%;
  min-height: 44px;
  padding: .5rem .6rem;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--bg);
  color: var(--ink);
}
.demo-status {
  margin-top: .75rem;
  padding: .55rem .7rem;
  border: 1px dashed var(--line);
  border-radius: 8px;
  font-size: .87rem;
  background: var(--bg);
  min-height: 3rem;
}
.demo-status.err { border-color: var(--bad); color: var(--bad); }
.demo-status.accept { border-color: var(--ok); }
.path { display: flex; flex-wrap: wrap; gap: .3rem; margin: .4rem 0 0; font-family: var(--mono); font-size: .82rem; }
.path span { padding: .1rem .35rem; border: 1px solid var(--line); border-radius: 5px; }
.path span.cur { border-color: var(--accent); background: var(--accent-soft); }
.path span.fin { border-color: var(--ok); color: var(--ok); }
tr.row-hl { background: var(--mark); }
tr.row-hl td { font-weight: 600; }

/* ---------- 术语与来源 ---------- */
.glossary { margin-top: 2rem; }
.glossary h2, .sources h2, .meta-foot h2 { font-size: clamp(1.15rem, 1rem + .6vw, 1.4rem); }
.glossary table { font-size: .86rem; }
.glossary td:first-child { white-space: normal; }
.gterm { font-weight: 700; }
.gen { display: block; font-size: .78rem; color: var(--muted); font-family: var(--mono); }
.sources { margin-top: 2.5rem; border-top: 2px solid var(--line); padding-top: 1.2rem; }
.sources ul { font-size: .87rem; }
.chips { display: flex; flex-wrap: wrap; gap: .4rem; margin: .6rem 0 1rem; padding: 0; list-style: none; }
.chips li { margin: 0; }
.chips a, .chips span {
  display: inline-block;
  font-size: .8rem;
  padding: .3rem .55rem;
  min-height: 36px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--paper);
  text-decoration: none;
  color: var(--ink);
}
.foot-meta { display: grid; grid-template-columns: 8.5rem minmax(0, 1fr); gap: .35rem .8rem; font-size: .84rem; margin: .8rem 0 0; }
.foot-meta dt { color: var(--muted); }
.foot-meta dd { margin: 0; }
@media (max-width: 520px) {
  .foot-meta { grid-template-columns: minmax(0, 1fr); }
  .foot-meta dt { margin-top: .4rem; }
}
.to-top { position: fixed; right: 1rem; bottom: 1rem; z-index: 30; min-width: 44px; padding: .5rem .7rem; box-shadow: var(--shadow); }

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

/* ---------- 打印 ---------- */
@media print {
  @page { margin: 16mm 14mm; }
  body { background: #fff; color: #000; font-size: 10.5pt; }
  .top, .side, .to-top, .demo-row, .q-actions, .search, .menu-btn { display: none !important; }
  .layout { display: block; max-width: none; padding: 0; }
  .lede, .note, .concept, .quiz, .demo, .tw, figure.tree { background: #fff; box-shadow: none; }
  article.sec { break-inside: auto; }
  article.sec h3, .chapter-head h2 { break-after: avoid; }
  .tw, pre.code, figure.tree { break-inside: avoid; }
  .fb { display: block; }
  a { color: #000; text-decoration: none; }
  .chips a { border: 0; padding: 0; }
}