/* 6.S184 学习文档 — 简约样式表 */

:root {
  --bg: #ffffff;
  --bg-soft: #f7f8fa;
  --bg-code: #f5f6f8;
  --fg: #1c1e21;
  --fg-soft: #5a6069;
  --fg-faint: #8a9099;
  --line: #e3e6ea;
  --accent: #2b5fd9;
  --accent-soft: #eaf0ff;
  --green: #1a7f52;
  --green-soft: #e9f6ef;
  --amber: #a8690a;
  --amber-soft: #fdf3e2;
  --red: #b23434;
  --red-soft: #fdeeee;
  --purple: #6b46c1;
  --purple-soft: #f2edfd;
  --maxw: 860px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #16181c;
    --bg-soft: #1d2025;
    --bg-code: #1f2229;
    --fg: #e4e6eb;
    --fg-soft: #a8aeb8;
    --fg-faint: #757c87;
    --line: #2c3038;
    --accent: #7ba3ff;
    --accent-soft: #1e2740;
    --green: #5cc999;
    --green-soft: #16281f;
    --amber: #e0ab5c;
    --amber-soft: #2a2318;
    --red: #e88b8b;
    --red-soft: #2b1c1c;
    --purple: #b79dff;
    --purple-soft: #241d33;
  }
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 24px; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue",
    "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  font-size: 16.5px;
  line-height: 1.85;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* ---------- 布局 ---------- */

.wrap {
  display: grid;
  grid-template-columns: 250px minmax(0, 1fr);
  gap: 48px;
  max-width: 1220px;
  margin: 0 auto;
  padding: 0 32px;
}

main {
  max-width: var(--maxw);
  padding: 48px 0 120px;
  min-width: 0;
}

/* ---------- 侧边目录 ---------- */

nav.toc {
  position: sticky;
  top: 0;
  align-self: start;
  max-height: 100vh;
  overflow-y: auto;
  padding: 48px 0 48px;
  font-size: 13.5px;
  line-height: 1.6;
  scrollbar-width: thin;
}

nav.toc .toc-title {
  font-size: 11px;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--fg-faint);
  font-weight: 600;
  margin-bottom: 12px;
}

nav.toc a {
  display: block;
  padding: 4px 0 4px 12px;
  color: var(--fg-soft);
  text-decoration: none;
  border-left: 2px solid var(--line);
  transition: color .15s, border-color .15s;
}

nav.toc a:hover { color: var(--accent); border-left-color: var(--accent); }
nav.toc a.lv3 { padding-left: 26px; font-size: 12.5px; color: var(--fg-faint); }
nav.toc a.active { color: var(--accent); border-left-color: var(--accent); font-weight: 500; }

/* ---------- 头部 ---------- */

header.doc-head {
  border-bottom: 1px solid var(--line);
  padding-bottom: 28px;
  margin-bottom: 40px;
}

.crumb {
  font-size: 13px;
  color: var(--fg-faint);
  margin-bottom: 14px;
}
.crumb a { color: var(--fg-faint); text-decoration: none; }
.crumb a:hover { color: var(--accent); }

.eyebrow {
  display: inline-block;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: .1em;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 3px 10px;
  border-radius: 4px;
  margin-bottom: 14px;
}

header.doc-head h1 {
  font-size: 2.05rem;
  line-height: 1.3;
  margin: 0 0 12px;
  letter-spacing: -.01em;
}

.subtitle { color: var(--fg-soft); font-size: 1.02rem; margin: 0 0 16px; }

.meta {
  font-size: 13.5px;
  color: var(--fg-faint);
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
}
.meta a { color: var(--fg-faint); }

/* ---------- 正文排版 ---------- */

h2 {
  font-size: 1.5rem;
  margin: 3em 0 .8em;
  padding-top: .3em;
  letter-spacing: -.01em;
  border-top: 1px solid var(--line);
  padding-top: 1.6rem;
}
main > section:first-of-type > h2 { border-top: none; padding-top: 0; margin-top: 1.5em; }

h3 { font-size: 1.18rem; margin: 2.2em 0 .6em; }
h4 { font-size: 1.02rem; margin: 1.8em 0 .5em; color: var(--fg-soft); }

p { margin: 1em 0; }

a { color: var(--accent); text-decoration: none; border-bottom: 1px solid transparent; }
a:hover { border-bottom-color: currentColor; }

ul, ol { padding-left: 1.5em; margin: 1em 0; }
li { margin: .45em 0; }
li > ul, li > ol { margin: .4em 0; }

strong { font-weight: 650; }
em { font-style: normal; color: var(--fg-soft); }

hr { border: none; border-top: 1px solid var(--line); margin: 3em 0; }

code {
  font-family: "SF Mono", "JetBrains Mono", Menlo, Consolas, "Liberation Mono", monospace;
  font-size: .875em;
  background: var(--bg-code);
  padding: .15em .4em;
  border-radius: 4px;
  border: 1px solid var(--line);
}

pre {
  background: var(--bg-code);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 16px 18px;
  overflow-x: auto;
  font-size: 13.5px;
  line-height: 1.65;
  margin: 1.4em 0;
}
pre code { background: none; border: none; padding: 0; font-size: inherit; }

blockquote {
  margin: 1.4em 0;
  padding: .2em 0 .2em 1.2em;
  border-left: 3px solid var(--line);
  color: var(--fg-soft);
}

/* ---------- 表格 ---------- */

.table-wrap { overflow-x: auto; margin: 1.5em 0; }

table {
  border-collapse: collapse;
  width: 100%;
  font-size: 14.5px;
  line-height: 1.6;
}
th, td {
  border-bottom: 1px solid var(--line);
  padding: 9px 12px;
  text-align: left;
  vertical-align: top;
}
thead th {
  border-bottom: 2px solid var(--line);
  font-weight: 600;
  color: var(--fg-soft);
  font-size: 13px;
  letter-spacing: .02em;
  white-space: nowrap;
}
tbody tr:hover { background: var(--bg-soft); }

/* ---------- 提示框 ---------- */

.box {
  margin: 1.6em 0;
  padding: 14px 18px;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: var(--bg-soft);
  font-size: 15.5px;
}
.box > :first-child { margin-top: 0; }
.box > :last-child { margin-bottom: 0; }
.box .box-title {
  font-weight: 650;
  font-size: 13px;
  letter-spacing: .04em;
  margin-bottom: .5em;
  display: block;
}

.box.key    { background: var(--accent-soft); border-color: transparent; }
.box.key .box-title { color: var(--accent); }
.box.tip    { background: var(--green-soft); border-color: transparent; }
.box.tip .box-title { color: var(--green); }
.box.warn   { background: var(--amber-soft); border-color: transparent; }
.box.warn .box-title { color: var(--amber); }
.box.pitfall { background: var(--red-soft); border-color: transparent; }
.box.pitfall .box-title { color: var(--red); }
.box.math   { background: var(--purple-soft); border-color: transparent; }
.box.math .box-title { color: var(--purple); }

/* ---------- 公式 ---------- */

mjx-container[display="true"] {
  overflow-x: auto;
  overflow-y: hidden;
  padding: 4px 0;
  margin: 1.2em 0 !important;
}
.formula {
  margin: 1.4em 0;
  padding: 2px 0;
  overflow-x: auto;
}

/* ---------- 卡片 / 索引页 ---------- */

.cards { display: grid; gap: 14px; margin: 2em 0; }

.card {
  display: block;
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 16px 20px;
  text-decoration: none;
  color: inherit;
  transition: border-color .15s, background .15s, transform .15s;
}
.card:hover {
  border-color: var(--accent);
  background: var(--bg-soft);
  transform: translateY(-1px);
}
.card .card-num {
  font-size: 12px;
  font-weight: 700;
  color: var(--accent);
  letter-spacing: .08em;
}
.card .card-title { font-size: 1.06rem; font-weight: 600; margin: 3px 0 5px; }
.card .card-desc { font-size: 14px; color: var(--fg-soft); line-height: 1.6; margin: 0; }
.card .card-tags { margin-top: 8px; font-size: 12px; color: var(--fg-faint); }

.unit-label {
  font-size: 11.5px;
  font-weight: 700;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--fg-faint);
  margin: 2.4em 0 .2em;
  padding-bottom: .4em;
  border-bottom: 1px solid var(--line);
}

/* ---------- 页脚导航 ---------- */

.pager {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 5em;
  padding-top: 24px;
  border-top: 1px solid var(--line);
  font-size: 14.5px;
}
.pager a {
  flex: 1;
  padding: 12px 16px;
  border: 1px solid var(--line);
  border-radius: 8px;
  text-decoration: none;
  color: inherit;
}
.pager a:hover { border-color: var(--accent); }
.pager .dir { display: block; font-size: 12px; color: var(--fg-faint); margin-bottom: 2px; }
.pager .nxt { text-align: right; }

footer.site {
  border-top: 1px solid var(--line);
  margin-top: 4em;
  padding: 24px 0 60px;
  font-size: 13px;
  color: var(--fg-faint);
}

/* ---------- 小组件 ---------- */

.kbd-list { list-style: none; padding-left: 0; }
.kbd-list li { padding-left: 1.5em; position: relative; }
.kbd-list li::before {
  content: "→";
  position: absolute;
  left: 0;
  color: var(--accent);
}

.tag {
  display: inline-block;
  font-size: 12px;
  padding: 2px 8px;
  border-radius: 999px;
  background: var(--bg-soft);
  border: 1px solid var(--line);
  color: var(--fg-soft);
  margin-right: 6px;
}

.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; margin: 1.5em 0; }

figure { margin: 1.8em 0; }
figure img { max-width: 100%; border-radius: 8px; border: 1px solid var(--line); }
figcaption { font-size: 13.5px; color: var(--fg-faint); margin-top: 8px; text-align: center; }

/* ---------- 环境图 ---------- */

.envdiag {
  margin: 1.6em 0;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--bg-soft);
  overflow-x: auto;
}
.envdiag .envdiag-title {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .06em;
  color: var(--purple);
  display: block;
  margin-bottom: 10px;
}
.envdiag pre {
  margin: 0;
  background: none;
  border: none;
  padding: 0;
  font-size: 13px;
  line-height: 1.6;
}

/* 帧：并排展示 global frame 与各函数帧 */
.frames { display: flex; flex-wrap: wrap; gap: 14px; margin: 1.4em 0; }
.frame {
  flex: 1 1 220px;
  border: 1px solid var(--line);
  border-radius: 8px;
  overflow: hidden;
  background: var(--bg);
}
.frame .frame-head {
  background: var(--bg-soft);
  padding: 6px 12px;
  font-weight: 650;
  font-size: 12.5px;
  border-bottom: 1px solid var(--line);
  font-family: "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;
}
.frame .frame-head .parent { font-weight: 400; color: var(--fg-faint); }
.frame table { font-size: 13px; }
.frame td { padding: 5px 12px; border-bottom: 1px solid var(--line); }
.frame tr:last-child td { border-bottom: none; }
.frame td:first-child {
  font-family: "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;
  color: var(--accent);
  width: 42%;
}

/* ---------- 分步推演 ---------- */

.steps { margin: 1.5em 0; }
.step {
  position: relative;
  padding: 10px 0 10px 42px;
  border-bottom: 1px solid var(--line);
}
.step:last-child { border-bottom: none; }
.step .step-n {
  position: absolute;
  left: 0;
  top: 12px;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 12.5px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
}
.step > :first-child { margin-top: 0; }
.step > :last-child { margin-bottom: 0; }

/* ---------- 自测题 / 折叠答案 ---------- */

details {
  margin: 1em 0;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 10px 16px;
  background: var(--bg-soft);
}
details[open] { padding-bottom: 14px; }
details > summary {
  cursor: pointer;
  font-size: 14px;
  font-weight: 600;
  color: var(--accent);
  list-style: none;
}
details > summary::-webkit-details-marker { display: none; }
details > summary::before { content: "\25B8  "; }
details[open] > summary::before { content: "\25BE  "; }

/* ---------- 状态徽章 ---------- */

.badge-pass, .badge-fail {
  display: inline-block;
  font-size: 12px;
  font-weight: 650;
  padding: 2px 9px;
  border-radius: 999px;
  margin-left: 8px;
  vertical-align: middle;
}
.badge-pass { background: var(--green-soft); color: var(--green); }
.badge-fail { background: var(--red-soft); color: var(--red); }

/* ---------- 响应式 ---------- */

@media (max-width: 1000px) {
  .wrap { grid-template-columns: 1fr; gap: 0; padding: 0 22px; }
  nav.toc {
    position: static;
    max-height: none;
    padding: 24px 0 0;
    border-bottom: 1px solid var(--line);
  }
  nav.toc a.lv3 { display: none; }
  main { padding-top: 32px; }
  .two-col { grid-template-columns: 1fr; }
}

@media (max-width: 600px) {
  body { font-size: 16px; }
  header.doc-head h1 { font-size: 1.6rem; }
  h2 { font-size: 1.3rem; }
  .pager { flex-direction: column; }
}

@media print {
  nav.toc, .pager { display: none; }
  .wrap { display: block; }
  body { font-size: 11pt; }
}