/* ==========================================================================
   AI Agent 工程课程 — 共享样式表
   所有课程页面共用本文件，保证整套课程视觉一致。
   ========================================================================== */

:root {
  --nav-w: 310px;
  --ink: #1a1d21;
  --ink-soft: #4a5158;
  --ink-faint: #7b838c;
  --paper: #ffffff;
  --paper-alt: #fbfbfa;
  --rule: #e3e4e2;
  --accent: #2f6f5e;
  --accent-soft: #eaf2ef;
  --accent-warm: #b3541e;
  --code-bg: #f6f7f6;
  --serif: "Songti SC", "Noto Serif CJK SC", "Source Han Serif SC", Georgia, "Times New Roman", serif;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB",
          "Microsoft YaHei", "Noto Sans CJK SC", "Source Han Sans SC", sans-serif;
  --mono: "JetBrains Mono", "SF Mono", Menlo, Consolas, "Liberation Mono", "Noto Sans Mono CJK SC", monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 1.5rem; }

body {
  margin: 0;
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.75;
  color: var(--ink);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
}

/* --------------------------------------------------------------------------
   左侧导航栏
   -------------------------------------------------------------------------- */

.nav-toggle {
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 60;
  display: none;
  padding: 0.45rem 0.7rem;
  font-size: 0.85rem;
  font-family: var(--sans);
  color: var(--ink);
  background: var(--paper);
  border: 1px solid var(--rule);
  border-radius: 6px;
  cursor: pointer;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.08);
}

.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  width: var(--nav-w);
  overflow-y: auto;
  overscroll-behavior: contain;
  background: var(--paper-alt);
  border-right: 1px solid var(--rule);
  padding: 1.25rem 0 3rem;
  font-size: 0.875rem;
  z-index: 50;
}

.sidebar::-webkit-scrollbar { width: 8px; }
.sidebar::-webkit-scrollbar-thumb { background: #d8dad9; border-radius: 4px; }

.side-head {
  padding: 0 1.1rem 0.9rem;
  border-bottom: 1px solid var(--rule);
  margin-bottom: 0.7rem;
}

.side-title {
  font-family: var(--serif);
  font-size: 1.15rem;
  font-weight: 700;
  line-height: 1.35;
  margin: 0 0 0.3rem;
  color: var(--ink);
}

.side-title a { color: inherit; text-decoration: none; }

.side-sub {
  font-size: 0.78rem;
  color: var(--ink-faint);
  margin: 0;
}

.side-progress {
  margin-top: 0.7rem;
  font-size: 0.75rem;
  color: var(--ink-soft);
}

.progress-bar {
  margin-top: 0.35rem;
  height: 4px;
  border-radius: 2px;
  background: #e2e4e3;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  width: 0%;
  background: var(--accent);
  transition: width 0.3s ease;
}

.side-search {
  margin: 0 1.1rem 0.9rem;
}

.side-search input {
  width: 100%;
  padding: 0.4rem 0.6rem;
  font-size: 0.82rem;
  font-family: var(--sans);
  border: 1px solid var(--rule);
  border-radius: 6px;
  background: var(--paper);
  color: var(--ink);
}

.side-search input:focus {
  outline: 2px solid var(--accent-soft);
  border-color: var(--accent);
}

.nav-group { margin-bottom: 0.35rem; }

.nav-group-label {
  padding: 0.55rem 1.1rem 0.3rem;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-faint);
}

.nav-list { list-style: none; margin: 0; padding: 0; }

.nav-link {
  display: flex;
  gap: 0.5rem;
  align-items: baseline;
  padding: 0.3rem 1.1rem 0.3rem 1.1rem;
  color: var(--ink-soft);
  text-decoration: none;
  border-left: 3px solid transparent;
  line-height: 1.45;
}

.nav-link:hover { background: #f1f2f1; color: var(--ink); }

.nav-link.active {
  background: var(--accent-soft);
  border-left-color: var(--accent);
  color: var(--accent);
  font-weight: 600;
}

.nav-num {
  flex: 0 0 2.2rem;
  font-family: var(--mono);
  font-size: 0.75rem;
  color: var(--ink-faint);
}

.nav-link.active .nav-num { color: var(--accent); }

.nav-name { flex: 1; }

.nav-check {
  flex: 0 0 auto;
  font-size: 0.75rem;
  color: var(--accent);
  opacity: 0;
}

.nav-link.done .nav-check { opacity: 1; }

.nav-link.hidden, .nav-group.hidden { display: none; }

/* --------------------------------------------------------------------------
   正文
   -------------------------------------------------------------------------- */

.main {
  margin-left: var(--nav-w);
  padding: 2.2rem 3rem 6rem;
  max-width: 52rem;
}

@media (min-width: 1400px) {
  .main { max-width: 56rem; }
}

.crumbs {
  font-size: 0.78rem;
  color: var(--ink-faint);
  margin-bottom: 1.2rem;
  padding-bottom: 0.7rem;
  border-bottom: 1px solid var(--rule);
}

.crumbs a { color: var(--ink-soft); text-decoration: none; }
.crumbs a:hover { color: var(--accent); text-decoration: underline; }

h1, h2, h3, h4, h5 {
  font-family: var(--serif);
  line-height: 1.35;
  color: var(--ink);
}

h1 {
  font-size: 1.95rem;
  margin: 0 0 1rem;
  letter-spacing: -0.01em;
}

h2 {
  font-size: 1.42rem;
  margin: 2.6rem 0 0.9rem;
  padding-top: 0.6rem;
  border-top: 1px solid var(--rule);
}

h3 { font-size: 1.14rem; margin: 1.9rem 0 0.6rem; }
h4 { font-size: 1.02rem; margin: 1.5rem 0 0.5rem; color: var(--ink-soft); }

.anchor-link {
  opacity: 0;
  margin-left: 0.4rem;
  font-size: 0.8em;
  color: var(--ink-faint);
  text-decoration: none;
}

h2:hover .anchor-link, h3:hover .anchor-link, h4:hover .anchor-link { opacity: 1; }

p { margin: 0.85rem 0; }

a { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: 2px; }
a:hover { color: var(--accent-warm); }

ul, ol { margin: 0.85rem 0; padding-left: 1.5rem; }
li { margin: 0.3rem 0; }
li > p:only-child { margin: 0; }
li > ul, li > ol { margin: 0.25rem 0; }

hr {
  border: 0;
  border-top: 1px solid var(--rule);
  margin: 2rem 0;
}

strong { font-weight: 650; color: var(--ink); }

em { font-style: italic; }

/* 引用块：课程里的 "> **课程目标**" 等元信息 */
blockquote {
  margin: 1.1rem 0;
  padding: 0.85rem 1.1rem;
  background: var(--paper-alt);
  border-left: 3px solid var(--accent);
  border-radius: 0 6px 6px 0;
  color: var(--ink-soft);
}

blockquote p { margin: 0.3rem 0; }

/* 代码 */
code {
  font-family: var(--mono);
  font-size: 0.86em;
  background: var(--code-bg);
  padding: 0.12em 0.38em;
  border-radius: 4px;
  border: 1px solid #ebeced;
}

pre {
  position: relative;
  margin: 1.1rem 0;
  padding: 1rem 1.1rem;
  background: var(--code-bg);
  border: 1px solid var(--rule);
  border-radius: 8px;
  overflow-x: auto;
  line-height: 1.6;
}

pre code {
  background: none;
  border: 0;
  padding: 0;
  font-size: 0.84rem;
}

.copy-btn {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  padding: 0.15rem 0.5rem;
  font-size: 0.7rem;
  font-family: var(--sans);
  color: var(--ink-faint);
  background: var(--paper);
  border: 1px solid var(--rule);
  border-radius: 4px;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.15s ease;
}

pre:hover .copy-btn { opacity: 1; }
.copy-btn:hover { color: var(--accent); border-color: var(--accent); }

/* 表格 */
table {
  width: 100%;
  margin: 1.2rem 0;
  border-collapse: collapse;
  font-size: 0.9rem;
}

th, td {
  border: 1px solid var(--rule);
  padding: 0.5rem 0.7rem;
  text-align: left;
  vertical-align: top;
}

th { background: var(--paper-alt); font-weight: 650; }
tbody tr:nth-child(even) { background: #fcfcfb; }

/* details 折叠块（参考答案等） */
details {
  margin: 1rem 0;
  padding: 0.7rem 1rem;
  background: var(--paper-alt);
  border: 1px solid var(--rule);
  border-radius: 8px;
}

details > summary {
  cursor: pointer;
  font-weight: 600;
  color: var(--accent);
  list-style: none;
}

details > summary::-webkit-details-marker { display: none; }
details > summary::before { content: "▸ "; color: var(--ink-faint); }
details[open] > summary::before { content: "▾ "; }
details > summary:hover { color: var(--accent-warm); }

details > *:not(summary) { margin-top: 0.8rem; }

/* 术语卡片（reference/glossary.html） */
.term-card {
  margin: 1rem 0;
  padding: 0.9rem 1.2rem;
  border: 1px solid var(--rule);
  border-left: 3px solid var(--accent);
  border-radius: 0 8px 8px 0;
  background: var(--paper);
}

.term-card h3 {
  margin: 0 0 0.5rem;
  font-size: 1.05rem;
}

.term-card ul { margin: 0; padding-left: 1.2rem; }
.term-card li { margin: 0.2rem 0; font-size: 0.92rem; color: var(--ink-soft); }
.term-card li p { margin: 0; }

/* 目录 */
.toc {
  margin: 1.6rem 0 2rem;
  padding: 0.9rem 1.2rem;
  background: var(--paper-alt);
  border: 1px solid var(--rule);
  border-radius: 8px;
}

.toc-label {
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin-bottom: 0.4rem;
}

.toc ol { margin: 0; padding-left: 1.2rem; font-size: 0.9rem; }
.toc li { margin: 0.15rem 0; }
.toc a { color: var(--ink-soft); text-decoration: none; }
.toc a:hover { color: var(--accent); text-decoration: underline; }

/* 课程头部元信息条 */
.lesson-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 0 0 1.6rem;
  padding: 0;
  list-style: none;
}

.meta-chip {
  font-size: 0.78rem;
  color: var(--ink-soft);
  background: var(--paper-alt);
  border: 1px solid var(--rule);
  border-radius: 999px;
  padding: 0.15rem 0.7rem;
}

.meta-chip b { color: var(--ink); font-weight: 600; }

/* 底部：完成按钮 + 上下课导航 */
.lesson-footer { margin-top: 3.5rem; }

.done-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.5rem 1.1rem;
  font-size: 0.9rem;
  font-family: var(--sans);
  color: var(--paper);
  background: var(--accent);
  border: 1px solid var(--accent);
  border-radius: 6px;
  cursor: pointer;
}

.done-btn:hover { background: #275a4c; }
.done-btn.done { background: var(--paper); color: var(--accent); }

.lesson-nav {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 2rem;
  padding-top: 1.2rem;
  border-top: 1px solid var(--rule);
  font-size: 0.9rem;
}

.lesson-nav a {
  text-decoration: none;
  color: var(--ink-soft);
  max-width: 45%;
}

.lesson-nav a:hover { color: var(--accent); }
.lesson-nav .dir { display: block; font-size: 0.72rem; color: var(--ink-faint); }
.lesson-nav .next { text-align: right; margin-left: auto; }

.ask-box {
  margin-top: 2rem;
  padding: 1rem 1.2rem;
  background: #f6f8fb;
  border: 1px solid #dfe6ef;
  border-radius: 8px;
  font-size: 0.9rem;
  color: var(--ink-soft);
}

.ask-box b { color: var(--ink); }

/* 首页（课程索引）卡片网格 */
.module-block { margin-bottom: 2.2rem; }

.module-head {
  display: flex;
  align-items: baseline;
  gap: 0.6rem;
  padding-bottom: 0.4rem;
  margin-bottom: 0.8rem;
  border-bottom: 1px solid var(--rule);
}

.module-head h2 { margin: 0; border: 0; padding: 0; font-size: 1.2rem; }
.module-head .mod-no { font-family: var(--mono); font-size: 0.8rem; color: var(--ink-faint); }

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 0.8rem;
}

.card {
  display: block;
  padding: 0.8rem 1rem;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: var(--paper);
  text-decoration: none;
  color: var(--ink);
  transition: border-color 0.15s ease, box-shadow 0.15s ease, transform 0.15s ease;
}

.card:hover {
  border-color: var(--accent);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
  transform: translateY(-1px);
}

.card .c-no { font-family: var(--mono); font-size: 0.72rem; color: var(--accent); }
.card .c-name { display: block; font-weight: 600; margin-top: 0.15rem; line-height: 1.4; }
.card .c-desc { display: block; font-size: 0.8rem; color: var(--ink-faint); margin-top: 0.25rem; }

.card.path-card { border-left: 3px solid var(--accent); }
.card.path-card .c-no { font-weight: 700; letter-spacing: 0.04em; }

.module-note {
  margin: 0 0 0.9rem;
  font-size: 0.9rem;
  color: var(--ink-soft);
}

.hero {
  padding: 1.4rem 1.6rem;
  margin-bottom: 2rem;
  background: var(--paper-alt);
  border: 1px solid var(--rule);
  border-radius: 10px;
}

.hero h1 { margin-bottom: 0.4rem; }
.hero p { color: var(--ink-soft); margin: 0.3rem 0; }

/* --------------------------------------------------------------------------
   自测题组件
   -------------------------------------------------------------------------- */

.quiz {
  margin: 1.6rem 0;
  padding: 1.1rem 1.3rem;
  background: #fffdf7;
  border: 1px solid #e8dfc8;
  border-radius: 10px;
}

.quiz-label {
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--accent-warm);
  margin-bottom: 0.6rem;
}

.quiz-q { font-weight: 600; margin: 0 0 0.6rem; }

.quiz-opts { display: grid; gap: 0.4rem; margin-bottom: 0.5rem; }

.quiz-opt {
  display: flex;
  gap: 0.55rem;
  align-items: flex-start;
  padding: 0.45rem 0.7rem;
  border: 1px solid var(--rule);
  border-radius: 6px;
  background: var(--paper);
  cursor: pointer;
  font-size: 0.92rem;
  transition: border-color 0.12s ease, background 0.12s ease;
}

.quiz-opt:hover { border-color: var(--accent); }
.quiz-opt.correct { border-color: var(--accent); background: var(--accent-soft); }
.quiz-opt.wrong { border-color: #c0392b; background: #fdf0ee; }
.quiz-opt .marker { font-family: var(--mono); color: var(--ink-faint); }
.quiz-opt.correct .marker { color: var(--accent); }
.quiz-opt.wrong .marker { color: #c0392b; }

.quiz-feedback {
  display: none;
  margin-top: 0.5rem;
  padding: 0.6rem 0.8rem;
  font-size: 0.9rem;
  border-radius: 6px;
  background: var(--paper);
  border: 1px solid var(--rule);
}

.quiz-feedback.show { display: block; }
.quiz-feedback.ok { border-color: var(--accent); background: var(--accent-soft); }
.quiz-feedback.no { border-color: #c0392b; background: #fdf0ee; }

/* --------------------------------------------------------------------------
   响应式
   -------------------------------------------------------------------------- */

@media (max-width: 1000px) {
  .nav-toggle { display: block; }
  .sidebar {
    transform: translateX(-100%);
    transition: transform 0.22s ease;
    box-shadow: 0 0 24px rgba(0, 0, 0, 0.12);
  }
  body.nav-open .sidebar { transform: translateX(0); }
  .main { margin-left: 0; padding: 3.6rem 1.3rem 5rem; }
  .nav-scrim {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.3);
    z-index: 40;
    display: none;
  }
  body.nav-open .nav-scrim { display: block; }
}

/* --------------------------------------------------------------------------
   打印：隐藏导航，正文全宽
   -------------------------------------------------------------------------- */

@media print {
  .sidebar, .nav-toggle, .nav-scrim, .lesson-nav, .done-btn, .copy-btn { display: none !important; }
  .main { margin: 0; padding: 0; max-width: none; }
  body { font-size: 11.5pt; }
  h2 { break-after: avoid; }
  pre, blockquote, table { break-inside: avoid; }
  a { color: inherit; text-decoration: underline; }
}