:root {
  --bg: #f7f7f2;
  --paper: #fffdfa;
  --ink: #20231f;
  --muted: #687067;
  --line: #deded3;
  --accent: #0f766e;
  --accent-2: #9a3412;
  --accent-soft: #d9f0ec;
  --sidebar: #eef2e8;
  --shadow: 0 18px 45px rgba(32, 35, 31, 0.10);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: "Inter", "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  line-height: 1.75;
}

a {
  color: inherit;
}

.progress {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 20;
  height: 4px;
  width: 0;
  background: var(--accent);
}

.menu-button {
  display: none;
}

.sidebar {
  position: fixed;
  inset: 0 auto 0 0;
  width: 315px;
  overflow-y: auto;
  border-right: 1px solid var(--line);
  background: var(--sidebar);
  padding: 24px 18px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  margin-bottom: 24px;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 48px;
  height: 48px;
  border-radius: 8px;
  background: var(--accent);
  color: white;
  font-weight: 800;
  letter-spacing: 0;
}

.brand strong,
.brand em {
  display: block;
}

.brand em {
  color: var(--muted);
  font-size: 12px;
  font-style: normal;
}

.search {
  display: block;
  margin-bottom: 16px;
}

.search span {
  display: block;
  color: var(--muted);
  font-size: 13px;
  margin-bottom: 6px;
}

.search input {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--paper);
  color: var(--ink);
  padding: 11px 12px;
  font-size: 14px;
  outline: none;
}

.search input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}

.search-results {
  display: grid;
  gap: 8px;
  margin-bottom: 14px;
}

.search-result {
  display: block;
  padding: 10px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255, 253, 250, 0.72);
  text-decoration: none;
}

.search-result strong {
  display: block;
  font-size: 13px;
}

.search-result span {
  color: var(--muted);
  font-size: 12px;
}

.nav {
  display: grid;
  gap: 7px;
}

.nav-link {
  display: grid;
  grid-template-columns: 34px 1fr;
  gap: 10px;
  align-items: center;
  min-height: 48px;
  padding: 9px;
  border-radius: 8px;
  color: #30362f;
  text-decoration: none;
}

.nav-link:hover,
.nav-link.active {
  background: var(--paper);
  box-shadow: 0 1px 0 rgba(32, 35, 31, 0.04);
}

.nav-link span {
  display: grid;
  place-items: center;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: #dfe6dc;
  color: var(--accent);
  font-weight: 800;
  font-size: 12px;
}

.nav-link.active span {
  background: var(--accent);
  color: white;
}

.nav-link strong {
  font-size: 13px;
  line-height: 1.3;
}

.page {
  min-height: 100vh;
  margin-left: 315px;
}

.hero {
  min-height: 72vh;
  display: grid;
  align-content: center;
  padding: 64px min(8vw, 92px) 48px;
  background:
    linear-gradient(120deg, rgba(15, 118, 110, 0.13), rgba(154, 52, 18, 0.08)),
    var(--paper);
  border-bottom: 1px solid var(--line);
}

.eyebrow,
.lecture-number {
  margin: 0 0 12px;
  color: var(--accent-2);
  font-weight: 800;
  letter-spacing: 0;
  text-transform: uppercase;
  font-size: 13px;
}

.hero h1 {
  max-width: 900px;
  margin: 0;
  font-size: clamp(42px, 6vw, 78px);
  line-height: 1.05;
  letter-spacing: 0;
}

.hero-copy {
  max-width: 760px;
  margin: 24px 0 0;
  color: #42483f;
  font-size: 19px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 34px;
}

.primary,
.secondary {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  border-radius: 8px;
  padding: 0 18px;
  text-decoration: none;
  font-weight: 700;
}

.primary {
  background: var(--accent);
  color: white;
}

.secondary {
  border: 1px solid var(--line);
  background: var(--paper);
}

.overview {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border-bottom: 1px solid var(--line);
}

.overview > div {
  background: var(--bg);
  padding: 34px min(5vw, 56px);
}

.overview h2 {
  margin: 0 0 8px;
  font-size: 22px;
}

.overview p {
  margin: 0;
  color: #464d45;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
  padding: 34px min(5vw, 56px) 64px;
}

.lecture-card {
  display: block;
  min-height: 230px;
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--paper);
  text-decoration: none;
  box-shadow: 0 1px 0 rgba(32, 35, 31, 0.04);
}

.lecture-card:hover {
  border-color: rgba(15, 118, 110, 0.45);
  box-shadow: var(--shadow);
  transform: translateY(-2px);
  transition: 150ms ease;
}

.lecture-card > span {
  display: inline-grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border-radius: 50%;
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 800;
  margin-bottom: 18px;
}

.lecture-card h2 {
  margin: 0 0 10px;
  font-size: 21px;
  line-height: 1.3;
}

.lecture-card p {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
}

.article {
  padding: 34px min(5vw, 60px) 74px;
}

.article-head {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  max-width: 1180px;
  margin: 0 auto 18px;
}

.back-home {
  color: var(--muted);
  text-decoration: none;
  font-weight: 700;
}

.article-layout {
  display: grid;
  grid-template-columns: minmax(0, 820px) 260px;
  gap: 42px;
  align-items: start;
  max-width: 1180px;
  margin: 0 auto;
}

.content {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: clamp(24px, 4vw, 54px);
  box-shadow: 0 2px 0 rgba(32, 35, 31, 0.03);
}

.visual-figure {
  margin: 0 0 34px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fbfcf7;
  overflow: hidden;
}

.visual-figure img {
  display: block;
  width: 100%;
  height: auto;
}

.visual-figure figcaption {
  border-top: 1px solid var(--line);
  padding: 12px 16px;
  color: #4d554c;
  font-size: 14px;
  line-height: 1.55;
  background: rgba(255, 253, 250, 0.86);
}

.wiki-figure {
  margin: -16px 0 38px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fffdfa;
  overflow: hidden;
}

.wiki-image-frame {
  display: grid;
  place-items: center;
  background: #f6f7f1;
  padding: 18px;
}

.wiki-figure img {
  display: block;
  max-width: 100%;
  max-height: 520px;
  width: auto;
  height: auto;
  object-fit: contain;
}

.wiki-figure figcaption {
  border-top: 1px solid var(--line);
  padding: 12px 16px;
  color: #434a42;
  font-size: 14px;
  line-height: 1.6;
  background: white;
}

.wiki-figure figcaption span {
  display: block;
  margin-top: 5px;
  color: var(--muted);
  font-size: 12px;
}

.wiki-figure figcaption a {
  color: var(--accent);
  font-weight: 700;
}

.slide-gallery {
  margin: -16px 0 42px;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #f7f8f2;
}

.slide-gallery-head {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  align-items: end;
  margin-bottom: 14px;
}

.slide-gallery-head h2 {
  margin: 0;
  padding: 0;
  border: 0;
  font-size: 22px;
}

.slide-gallery-head p {
  max-width: 460px;
  margin: 0;
  color: var(--muted);
  font-size: 13px;
  line-height: 1.5;
}

.slide-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}

.slide-card {
  margin: 0;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: white;
}

.slide-card img {
  display: block;
  width: 100%;
  height: auto;
}

.slide-card figcaption {
  border-top: 1px solid var(--line);
  padding: 10px 12px;
  font-size: 13px;
  line-height: 1.45;
}

.slide-card figcaption strong,
.slide-card figcaption span {
  display: block;
}

.slide-card figcaption span {
  margin-top: 3px;
  color: var(--muted);
  font-size: 12px;
}

.content h1 {
  margin: 0 0 20px;
  font-size: clamp(30px, 4vw, 48px);
  line-height: 1.16;
  letter-spacing: 0;
}

.content h2 {
  margin: 44px 0 14px;
  padding-top: 12px;
  border-top: 1px solid var(--line);
  font-size: 28px;
  line-height: 1.28;
}

.content h3 {
  margin: 30px 0 10px;
  font-size: 21px;
}

.content h4 {
  margin: 24px 0 8px;
  font-size: 17px;
}

.content p,
.content li {
  font-size: 16px;
}

.content p {
  margin: 13px 0;
}

.content ul {
  padding-left: 1.25rem;
}

.content code {
  border: 1px solid #e4e1d8;
  border-radius: 6px;
  background: #f4f1e9;
  padding: 0.12em 0.34em;
  font-size: 0.92em;
}

.content pre {
  overflow: auto;
  border-radius: 8px;
  background: #1f2623;
  color: #f8faf7;
  padding: 18px;
}

.content pre code {
  border: 0;
  background: transparent;
  color: inherit;
  padding: 0;
}

.table-wrap {
  overflow-x: auto;
  margin: 18px 0;
  border: 1px solid var(--line);
  border-radius: 8px;
}

table {
  width: 100%;
  border-collapse: collapse;
  background: white;
}

th,
td {
  padding: 10px 12px;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}

th {
  background: #edf3ed;
}

tr:last-child td {
  border-bottom: 0;
}

.toc {
  position: sticky;
  top: 22px;
  max-height: calc(100vh - 44px);
  overflow: auto;
  border-left: 3px solid var(--accent-soft);
  padding-left: 16px;
}

.toc strong {
  display: block;
  margin-bottom: 10px;
}

.toc a {
  display: block;
  color: var(--muted);
  text-decoration: none;
  font-size: 13px;
  line-height: 1.35;
  margin: 0 0 8px;
}

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

.toc-level-3 {
  padding-left: 12px;
}

.pager {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  margin-top: 46px;
  padding-top: 22px;
  border-top: 1px solid var(--line);
}

.pager a {
  display: flex;
  align-items: center;
  min-height: 54px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 12px;
  text-decoration: none;
  font-weight: 700;
}

.pager a:last-child {
  justify-content: flex-end;
  text-align: right;
}

@media (max-width: 1120px) {
  .card-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .article-layout {
    grid-template-columns: minmax(0, 1fr);
  }

  .toc {
    position: static;
    max-height: none;
    order: -1;
    background: var(--paper);
    border: 1px solid var(--line);
    border-radius: 8px;
    padding: 18px;
  }
}

@media (max-width: 760px) {
  .menu-button {
    position: fixed;
    z-index: 30;
    right: 14px;
    bottom: 14px;
    display: inline-flex;
    align-items: center;
    min-height: 42px;
    border: 0;
    border-radius: 999px;
    background: var(--accent);
    color: white;
    padding: 0 16px;
    font-weight: 800;
    box-shadow: var(--shadow);
  }

  .sidebar {
    z-index: 25;
    width: min(88vw, 330px);
    transform: translateX(-105%);
    transition: transform 180ms ease;
    box-shadow: var(--shadow);
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .page {
    margin-left: 0;
  }

  .hero {
    min-height: 68vh;
    padding: 42px 22px 32px;
  }

  .hero h1 {
    font-size: 40px;
  }

  .hero-copy {
    font-size: 16px;
  }

  .overview,
  .card-grid {
    grid-template-columns: 1fr;
  }

  .overview > div,
  .card-grid,
  .article {
    padding-left: 18px;
    padding-right: 18px;
  }

  .article-head {
    display: block;
  }

  .content {
    padding: 22px 18px;
  }

  .content h2 {
    font-size: 24px;
  }

  .pager {
    grid-template-columns: 1fr;
  }

  .pager a:last-child {
    justify-content: flex-start;
    text-align: left;
  }
}