/* ============================================================
   course.css — 推理框架课 · 共享样式
   所有 lesson 与 reference 文档都链接这一个文件。
   ============================================================ */

:root {
  --page-width: 76rem;
  --paper: #fdfcf8;
  --ink: #1b1b1b;
  --ink-soft: #57534b;
  --rule: #e5dfd3;
  --accent: #a63a2a;
  --accent-soft: #f7ece7;
  --ochre: #8a6d3b;
  --ochre-soft: #f8f2e4;
  --code-bg: #f4f1e9;
  --green: #2f6f4e;
  --red: #a63a2a;
  --green-soft: #eaf2ec;
  --mono: "JetBrains Mono", "Cascadia Code", "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  --serif: "Iowan Old Style", "Palatino Linotype", "Book Antiqua", "Noto Serif SC", "Source Han Serif SC", "Songti SC", Georgia, serif;
  --sans: "Inter", "Helvetica Neue", "Noto Sans SC", "PingFang SC", system-ui, sans-serif;
}

* { box-sizing: border-box; }

html { font-size: 17px; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  line-height: 1.78;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

.page {
  max-width: var(--page-width);
  margin: 0 auto;
  padding: 4rem 1.6rem 7rem;
}

/* ---------- 页头 ---------- */

.kicker {
  font-family: var(--sans);
  font-size: 0.72rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 0 0 0.9rem;
}

h1 {
  font-size: 2.45rem;
  line-height: 1.18;
  margin: 0 0 0.7rem;
  font-weight: 600;
  letter-spacing: -0.012em;
}

.dek {
  font-size: 1.16rem;
  color: var(--ink-soft);
  margin: 0 0 1.4rem;
  line-height: 1.6;
}

.meta {
  font-family: var(--sans);
  font-size: 0.78rem;
  color: var(--ink-soft);
  border-top: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
  padding: 0.6rem 0;
  margin: 0 0 2.8rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem 1.2rem;
}

/* ---------- 标题层级 ---------- */

h2 {
  font-size: 1.42rem;
  line-height: 1.35;
  margin: 3rem 0 1rem;
  font-weight: 600;
}

h2 .num {
  font-family: var(--mono);
  font-size: 0.72em;
  color: var(--accent);
  margin-right: 0.55em;
  font-weight: 400;
}

h3 {
  font-size: 1.08rem;
  margin: 2rem 0 0.6rem;
  font-weight: 600;
}

p { margin: 0 0 1.1rem; text-wrap: pretty; }

a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid rgba(166, 58, 42, 0.28);
  transition: border-color 0.15s ease;
}
a:hover { border-bottom-color: var(--accent); }

ul, ol { margin: 0 0 1.2rem; padding-left: 1.35rem; }
li { margin: 0.35rem 0; }
li::marker { color: var(--ink-soft); }

strong { font-weight: 600; }

/* ---------- 代码 ---------- */

code {
  font-family: var(--mono);
  font-size: 0.85em;
  background: #f1ede3;
  padding: 0.08em 0.32em;
  border-radius: 2px;
  color: #2a2a26;
}

pre {
  position: relative;
  background: var(--code-bg);
  border-left: 3px solid #d8d0bf;
  border-radius: 0 3px 3px 0;
  padding: 1.05rem 1.15rem 1rem;
  overflow-x: auto;
  font-size: 0.845rem;
  line-height: 1.72;
  margin: 0 0 1.5rem;
  tab-size: 4;
  scrollbar-width: thin;
}

pre code {
  background: none;
  padding: 0;
  font-size: 1em;
  color: inherit;
}

pre .file {
  display: block;
  font-family: var(--sans);
  font-size: 0.68rem;
  letter-spacing: 0.06em;
  color: var(--ink-soft);
  margin-bottom: 0.6rem;
  text-transform: uppercase;
}

pre .hl { background: rgba(166, 58, 42, 0.09); display: inline-block; width: 100%; }

/* ---------- 语法着色 ---------- */

pre .cm,
pre .tok-cm { color: #7d7668; }
pre .tok-kw { color: #9b2c2c; }
pre .tok-str { color: #2f6f4e; }
pre .tok-num { color: #8a6d3b; }
pre .tok-fn { color: #1f5f8b; }
pre .tok-bi { color: #6b4c9a; }
pre .tok-dec { color: #a63a2a; }
pre .tok-var { color: #7a4b1f; }
pre .tok-flag { color: #6b4c9a; }
pre .tok-pp { color: #9b2c2c; }

/* ---------- 复制按钮 ---------- */

.copy-btn {
  position: absolute;
  top: 0.45rem;
  right: 0.45rem;
  font-family: var(--sans);
  font-size: 0.68rem;
  letter-spacing: 0.04em;
  color: var(--ink-soft);
  background: rgba(253, 252, 248, 0.94);
  border: 1px solid var(--rule);
  border-radius: 3px;
  padding: 0.2rem 0.5rem;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}

pre:hover .copy-btn,
.copy-btn:focus-visible { opacity: 1; }
.copy-btn:hover { color: var(--accent); border-color: var(--accent); }
.copy-btn.copied { color: var(--green); border-color: var(--green); opacity: 1; }

@media (hover: none) {
  .copy-btn { opacity: 0.8; }
}

/* ---------- 本课目录 ---------- */

.lesson-toc {
  font-family: var(--sans);
  font-size: 0.79rem;
  line-height: 2;
  border-top: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
  padding: 0.5rem 0;
  margin: 0 0 2.6rem;
}

.lesson-toc .label {
  font-size: 0.66rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  margin-right: 0.9rem;
}

.lesson-toc a {
  border-bottom: none;
  color: var(--ink-soft);
  margin-right: 1rem;
  white-space: nowrap;
}

.lesson-toc a:hover { color: var(--accent); }

/* ---------- 阅读进度 ---------- */

.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 2px;
  width: 0;
  background: var(--accent);
  z-index: 60;
}

h2[id] { scroll-margin-top: 2rem; }

@media (prefers-reduced-motion: no-preference) {
  html { scroll-behavior: smooth; }
}

/* ---------- 引用 ---------- */

blockquote {
  margin: 1.6rem 0;
  padding: 0.1rem 0 0.1rem 1.1rem;
  border-left: 2px solid var(--rule);
  color: var(--ink-soft);
  font-size: 0.97rem;
}

blockquote p:last-child { margin-bottom: 0; }


/* ---------- 提示块 ---------- */

.key, .warn, .aside {
  padding: 0.95rem 1.15rem;
  margin: 1.6rem 0;
  font-size: 0.95rem;
  line-height: 1.7;
}

.key {
  background: var(--accent-soft);
  border-left: 3px solid var(--accent);
}

.warn {
  background: var(--ochre-soft);
  border-left: 3px solid var(--ochre);
}

.aside {
  background: var(--green-soft);
  border-left: 3px solid var(--green);
}

.key p:last-child, .warn p:last-child, .aside p:last-child { margin-bottom: 0; }

.key .label, .warn .label, .aside .label {
  display: block;
  font-family: var(--sans);
  font-size: 0.68rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-bottom: 0.35rem;
  opacity: 0.75;
}

/* ---------- 旁注 ---------- */

.sidenote {
  font-family: var(--sans);
  font-size: 0.78rem;
  line-height: 1.5;
  color: var(--ink-soft);
}

@media (min-width: 110rem) {
  .sidenote {
    float: right;
    clear: right;
    width: 12rem;
    margin-right: -14.5rem;
    margin-top: 0.3rem;
  }
}

/* ---------- 引擎循环图 ---------- */

.loop {
  display: grid;
  grid-template-columns: 1fr auto 1fr auto 1fr;
  align-items: center;
  gap: 0.5rem;
  margin: 2rem 0;
  font-family: var(--sans);
  font-size: 0.84rem;
}

.loop .box {
  border: 1px solid var(--rule);
  background: #fff;
  padding: 0.8rem 0.7rem;
  text-align: center;
  line-height: 1.4;
}

.loop .box b { display: block; font-size: 0.92rem; }
.loop .box span { color: var(--ink-soft); font-size: 0.76rem; }
.loop .arrow { color: var(--accent); font-size: 1.1rem; }

@media (max-width: 34rem) {
  .loop { grid-template-columns: 1fr; }
  .loop .arrow { transform: rotate(90deg); text-align: center; }
}

/* ---------- 表格 ---------- */

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
  margin: 0 0 1.6rem;
}

th, td {
  text-align: left;
  padding: 0.6rem 0.7rem;
  border-bottom: 1px solid var(--rule);
  vertical-align: top;
}

th {
  font-family: var(--sans);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-soft);
  border-bottom: 1px solid var(--ink-soft);
}

/* ---------- 折叠答案 ---------- */

details {
  border: 1px solid var(--rule);
  background: #fff;
  padding: 0.7rem 1rem;
  margin: 0.9rem 0;
  font-size: 0.94rem;
}

summary {
  cursor: pointer;
  font-family: var(--sans);
  font-size: 0.82rem;
  color: var(--accent);
  letter-spacing: 0.02em;
}

details p:last-child { margin-bottom: 0; }

/* ---------- 测验 ---------- */

.quiz {
  border-top: 2px solid var(--ink);
  padding-top: 1.2rem;
  margin: 2.4rem 0;
}

.quiz-q { margin-bottom: 1.9rem; }

.q-text {
  font-size: 1rem;
  margin-bottom: 0.8rem;
  font-weight: 600;
}

.options { display: grid; gap: 0.45rem; }

.option {
  display: flex;
  align-items: baseline;
  gap: 0.7rem;
  width: 100%;
  text-align: left;
  background: #fff;
  border: 1px solid var(--rule);
  padding: 0.62rem 0.8rem;
  font-family: var(--serif);
  font-size: 0.94rem;
  color: var(--ink);
  cursor: pointer;
  transition: background 0.12s ease, border-color 0.12s ease;
}

.option:hover { background: #fbf8f2; border-color: #cfc6b4; }
.option:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.option[disabled] { cursor: default; }

.option .tag {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--ink-soft);
  min-width: 1rem;
}

.option.correct {
  background: var(--green-soft);
  border-color: var(--green);
}
.option.correct .tag { color: var(--green); }

.option.wrong {
  background: #fbf0ed;
  border-color: var(--red);
}
.option.wrong .tag { color: var(--red); }

.feedback {
  font-family: var(--sans);
  font-size: 0.84rem;
  line-height: 1.6;
  color: var(--ink-soft);
  margin-top: 0.6rem;
  min-height: 1.2rem;
}

.feedback.ok { color: var(--green); }
.feedback.no { color: var(--red); }

.score {
  font-family: var(--sans);
  font-size: 0.9rem;
  border-top: 1px solid var(--rule);
  padding-top: 0.9rem;
  color: var(--ink-soft);
}

/* ---------- 术语表 ---------- */

.gloss { margin: 0 0 2rem; }

.gloss dt {
  font-weight: 600;
  margin-top: 1.35rem;
  line-height: 1.5;
}

.gloss dt .en {
  font-family: var(--mono);
  font-size: 0.82em;
  font-weight: 400;
  color: var(--accent);
}

.gloss dt .zh { color: var(--ink-soft); font-weight: 400; font-size: 0.92em; }

.gloss dd {
  margin: 0.25rem 0 0;
  font-size: 0.94rem;
  line-height: 1.7;
}

.gloss .where {
  display: block;
  font-family: var(--sans);
  font-size: 0.76rem;
  color: var(--ink-soft);
  margin-top: 0.2rem;
}

.gloss .where code { font-size: 0.9em; background: none; padding: 0; color: var(--accent); }

.toc {
  font-family: var(--sans);
  font-size: 0.86rem;
  border-top: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
  padding: 0.9rem 0;
  margin: 0 0 2.2rem;
}
.toc a { margin-right: 1.1rem; border-bottom: none; }

/* ---------- 课程导航 ---------- */

.lesson-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  font-family: var(--sans);
  font-size: 0.78rem;
  border-top: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
  padding: 0.55rem 0;
  margin: 0 0 2.6rem;
  color: var(--ink-soft);
}
.lesson-nav a { border-bottom: none; }
.lesson-nav .home { letter-spacing: 0.08em; text-transform: uppercase; }
.lesson-nav .right { margin-left: auto; }

/* ---------- 课程索引 ---------- */

.part {
  font-family: var(--sans);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 2.8rem 0 0.4rem;
  border-bottom: 1px solid var(--rule);
  padding-bottom: 0.4rem;
}

.lesson-card {
  display: grid;
  grid-template-columns: 2.6rem 1fr auto;
  gap: 0.2rem 0.9rem;
  align-items: baseline;
  padding: 0.85rem 0.4rem;
  border-bottom: 1px solid var(--rule);
  text-decoration: none;
  color: inherit;
  border-left: 2px solid transparent;
  transition: background 0.12s ease, border-color 0.12s ease;
}

.lesson-card:hover {
  background: #fff;
  border-left-color: var(--accent);
}

.lesson-card .no {
  font-family: var(--mono);
  font-size: 0.82rem;
  color: var(--accent);
}

.lesson-card .t {
  font-family: var(--serif);
  font-size: 1.04rem;
  font-weight: 600;
  line-height: 1.4;
}

.lesson-card .d {
  grid-column: 2 / 3;
  font-family: var(--sans);
  font-size: 0.82rem;
  color: var(--ink-soft);
  line-height: 1.5;
}

.lesson-card .m {
  grid-row: 1 / 2;
  font-family: var(--sans);
  font-size: 0.72rem;
  color: var(--ink-soft);
  white-space: nowrap;
}

@media (max-width: 34rem) {
  .lesson-card { grid-template-columns: 2.2rem 1fr; }
  .lesson-card .m { grid-row: auto; grid-column: 2 / 3; }
}

/* ---------- 页脚 ---------- */

.lesson-footer {
  margin-top: 3.5rem;
  border-top: 1px solid var(--rule);
  padding-top: 1.4rem;
  font-family: var(--sans);
  font-size: 0.85rem;
  color: var(--ink-soft);
}

.lesson-footer h3 { font-family: var(--sans); font-size: 0.78rem; letter-spacing: 0.1em; text-transform: uppercase; color: var(--ink); }
.lesson-footer ul { padding-left: 1.1rem; }

.ask-teacher {
  background: #fff;
  border: 1px dashed var(--accent);
  padding: 1rem 1.15rem;
  margin: 2.2rem 0;
  font-size: 0.92rem;
}
.ask-teacher strong { color: var(--accent); }

/* ---------- 打印 ---------- */

@media print {
  html { font-size: 12pt; }
  body { background: #fff; }
  .page { max-width: none; padding: 0; }
  .no-print { display: none !important; }
  a { color: var(--ink); border-bottom: none; }
  pre, .key, .warn, .aside, details { break-inside: avoid; }
  h2 { break-after: avoid; }
}