:root {
  --bg: #ffffff;
  --bg-soft: #f7f7f8;
  --panel: #ffffff;
  --text: #242428;
  --muted: #696970;
  --faint: #8d8d94;
  --border: #e5e5e7;
  --brand: #d65c32;
  --brand-dark: #9b3e20;
  --brand-soft: #fff1eb;
  --code: #191a1f;
  --code-text: #ececf1;
  --header: rgba(255, 255, 255, 0.92);
  --shadow: 0 16px 50px rgba(30, 24, 20, 0.08);
  --sans: "Inter", "PingFang SC", "Microsoft YaHei", ui-sans-serif, system-ui, sans-serif;
  --mono: "JetBrains Mono", "SFMono-Regular", Consolas, monospace;
}

[data-theme="dark"] {
  --bg: #19191c;
  --bg-soft: #222226;
  --panel: #202024;
  --text: rgba(255, 255, 248, 0.9);
  --muted: rgba(240, 240, 248, 0.64);
  --faint: rgba(240, 240, 248, 0.43);
  --border: #34343a;
  --brand: #f09974;
  --brand-dark: #ffb293;
  --brand-soft: #3b2922;
  --code: #111216;
  --code-text: #f2f2f5;
  --header: rgba(25, 25, 28, 0.92);
  --shadow: 0 18px 55px rgba(0, 0, 0, 0.24);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  color-scheme: light;
}

[data-theme="dark"] {
  color-scheme: dark;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 15px/1.78 var(--sans);
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
}

a:focus-visible,
button:focus-visible,
input:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--brand) 38%, transparent);
  outline-offset: 3px;
}

.skip-link {
  position: fixed;
  z-index: 100;
  top: 8px;
  left: 8px;
  padding: 8px 12px;
  border-radius: 8px;
  background: var(--brand);
  color: #fff;
  text-decoration: none;
  transform: translateY(-160%);
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  position: fixed;
  z-index: 40;
  inset: 0 0 auto;
  height: 64px;
  border-bottom: 1px solid var(--border);
  background: var(--header);
  backdrop-filter: blur(14px);
}

.header-inner {
  height: 100%;
  padding: 0 20px;
  display: flex;
  align-items: center;
  gap: 20px;
}

.site-brand,
.course-home {
  text-decoration: none;
}

.site-brand {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  font-weight: 800;
  white-space: nowrap;
}

.brand-mark {
  width: 29px;
  height: 29px;
  border-radius: 8px;
  display: grid;
  place-items: center;
  background: var(--brand);
  color: #fff;
  font: 900 16px/1 var(--mono);
}

.course-name {
  min-width: 0;
  overflow: hidden;
  color: var(--muted);
  font-weight: 600;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.header-actions {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 10px;
}

.library-link {
  color: var(--muted);
  font-size: 13px;
  font-weight: 650;
  text-decoration: none;
}

.library-link:hover {
  color: var(--brand);
}

.icon-button {
  width: 44px;
  height: 44px;
  padding: 0;
  border: 1px solid var(--border);
  border-radius: 9px;
  background: var(--panel);
  color: var(--muted);
  cursor: pointer;
  font: 700 16px/1 var(--sans);
}

.menu-button {
  display: none;
}

.course-layout {
  min-height: 100vh;
  padding-top: 64px;
}

.course-sidebar {
  position: fixed;
  z-index: 30;
  top: 64px;
  bottom: 0;
  left: 0;
  width: 326px;
  overflow: hidden;
  border-right: 1px solid var(--border);
  background: var(--bg-soft);
  display: flex;
  flex-direction: column;
}

.sidebar-head {
  padding: 22px 18px 15px;
  border-bottom: 1px solid var(--border);
}

.course-home {
  display: block;
  padding: 2px 3px 14px;
}

.course-home strong {
  display: block;
  margin-top: 7px;
  font-size: 17px;
  line-height: 1.4;
}

.course-badge {
  color: var(--brand);
  font: 700 11px/1.2 var(--mono);
  letter-spacing: 0.06em;
}

.search-box {
  display: block;
}

.search-box input {
  width: 100%;
  height: 38px;
  padding: 0 12px;
  border: 1px solid var(--border);
  border-radius: 9px;
  background: var(--panel);
  color: var(--text);
  font: 13px/1 var(--sans);
}

.search-box input::placeholder {
  color: var(--faint);
}

.course-nav {
  padding: 14px 12px 40px;
  overflow-y: auto;
  overscroll-behavior: contain;
  scrollbar-width: thin;
}

.nav-chapter {
  margin: 0 0 8px;
}

.nav-link {
  display: block;
  padding: 7px 9px;
  border-radius: 8px;
  color: var(--muted);
  font-size: 12.5px;
  line-height: 1.45;
  text-decoration: none;
}

.nav-link:hover {
  background: var(--panel);
  color: var(--text);
}

.nav-link.active {
  background: var(--brand-soft);
  color: var(--brand-dark);
  font-weight: 750;
}

.nav-chapter-link {
  color: var(--text);
  font-weight: 760;
}

.nav-children {
  margin: 2px 0 10px 11px;
  padding-left: 9px;
  border-left: 1px solid var(--border);
}

.nav-item[hidden],
.nav-chapter[hidden] {
  display: none;
}

.sidebar-backdrop {
  display: none;
}

.course-main {
  min-width: 0;
  margin-left: 326px;
}

.content-shell {
  width: min(100%, 960px);
  margin: 0 auto;
  padding: 44px 64px 80px;
}

.breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 7px;
  margin-bottom: 12px;
  color: var(--faint);
  font-size: 12px;
}

.breadcrumbs a {
  color: var(--muted);
  text-decoration: none;
}

.breadcrumbs a:hover {
  color: var(--brand);
}

.breadcrumb-separator {
  color: var(--border);
}

.page-meta {
  margin-bottom: 24px;
  color: var(--faint);
  font: 12px/1.4 var(--mono);
}

.course-content {
  overflow-wrap: anywhere;
}

.course-content > .document-title {
  margin: 0 0 34px;
  font-size: clamp(34px, 5vw, 54px);
  line-height: 1.12;
  letter-spacing: -0.038em;
}

.course-content h2,
.course-content h3,
.course-content h4 {
  scroll-margin-top: 88px;
  line-height: 1.35;
  letter-spacing: -0.015em;
}

.course-content h2 {
  margin: 46px 0 18px;
  font-size: 27px;
}

.course-content h3 {
  margin: 34px 0 14px;
  font-size: 22px;
}

.course-content p {
  margin: 0 0 18px;
}

.course-content strong {
  color: var(--text);
  font-weight: 760;
}

.course-content ul,
.course-content ol {
  margin: 0 0 20px;
  padding-left: 1.5em;
}

.course-content li {
  margin: 7px 0;
}

.course-content a {
  color: var(--brand-dark);
  text-underline-offset: 3px;
}

.course-content img,
.course-content video {
  display: block;
  width: auto;
  max-width: 100%;
  height: auto;
  margin: 0 auto;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--bg-soft);
}

.course-content figure {
  margin: 28px 0;
}

.course-content video {
  width: 100%;
  box-shadow: var(--shadow);
}

.course-content pre {
  margin: 24px 0;
  padding: 20px 22px;
  overflow-x: auto;
  border: 1px solid #2f3037;
  border-radius: 12px;
  background: var(--code);
  color: var(--code-text);
  font: 13px/1.75 var(--mono);
  tab-size: 2;
}

.course-content code {
  font-family: var(--mono);
}

.course-content p code,
.course-content li code {
  padding: 0.18em 0.42em;
  border-radius: 5px;
  background: var(--bg-soft);
  color: var(--brand-dark);
  font-size: 0.92em;
}

.document-link,
.subpage-link,
.attachment-link {
  display: flex;
  align-items: center;
  gap: 10px;
  min-height: 46px;
  margin: 6px 0;
  padding: 10px 13px;
  border: 1px solid var(--border);
  border-radius: 9px;
  background: var(--bg-soft);
  color: var(--text) !important;
  font-weight: 650;
  text-decoration: none;
}

.document-link::before,
.subpage-link::before {
  content: "→";
  color: var(--brand);
}

.attachment-link::before {
  content: "↓";
  color: var(--brand);
}

.document-link:hover,
.subpage-link:hover,
.attachment-link:hover {
  border-color: var(--brand);
  background: var(--brand-soft);
}

.subpage-list {
  margin: 18px 0 30px;
  display: grid;
  gap: 7px;
}

.page-navigation {
  margin-top: 70px;
  padding-top: 24px;
  border-top: 1px solid var(--border);
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.pager-link,
.pager-empty {
  min-height: 92px;
  padding: 16px 18px;
  border: 1px solid var(--border);
  border-radius: 12px;
}

.pager-link {
  display: flex;
  flex-direction: column;
  justify-content: center;
  color: var(--text);
  text-decoration: none;
}

.pager-link:hover {
  border-color: var(--brand);
  background: var(--brand-soft);
}

.pager-link.next {
  text-align: right;
}

.pager-direction {
  margin-bottom: 6px;
  color: var(--faint);
  font: 11px/1 var(--mono);
}

.pager-title {
  font-size: 13px;
  font-weight: 700;
  line-height: 1.5;
}

.pager-empty {
  border-style: dashed;
  opacity: 0.42;
}

.course-footer {
  margin-top: 36px;
  padding-top: 18px;
  border-top: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  gap: 20px;
  color: var(--faint);
  font-size: 12px;
}

.course-footer a {
  color: var(--muted);
  text-decoration: none;
}

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

@media (max-width: 980px) {
  .menu-button {
    display: inline-block;
  }

  .course-sidebar {
    width: min(88vw, 360px);
    transform: translateX(-105%);
    transition: transform 180ms ease;
    box-shadow: var(--shadow);
  }

  body.sidebar-open {
    overflow: hidden;
  }

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

  .sidebar-backdrop {
    position: fixed;
    z-index: 25;
    inset: 64px 0 0;
    width: 100%;
    height: auto;
    border: 0;
    background: rgba(0, 0, 0, 0.44);
  }

  body.sidebar-open .sidebar-backdrop {
    display: block;
  }

  .course-main {
    margin-left: 0;
  }
}

@media (max-width: 680px) {
  .site-header {
    height: 58px;
  }

  .header-inner {
    padding: 0 13px;
    gap: 11px;
  }

  .course-layout {
    padding-top: 58px;
  }

  .course-sidebar {
    top: 58px;
  }

  .site-brand > span:last-child,
  .library-link {
    display: none;
  }

  .course-name {
    font-size: 13px;
  }

  .content-shell {
    padding: 31px 20px 64px;
  }

  .course-content > .document-title {
    margin-bottom: 26px;
    font-size: 34px;
  }

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

  .course-content pre {
    margin-right: -20px;
    margin-left: -20px;
    border-right: 0;
    border-left: 0;
    border-radius: 0;
  }

  .page-navigation {
    grid-template-columns: 1fr;
  }

  .pager-link.next {
    text-align: left;
  }

  .course-footer {
    flex-direction: column;
    gap: 5px;
  }
}

@media print {
  .site-header,
  .course-sidebar,
  .sidebar-backdrop,
  .page-navigation,
  .course-footer {
    display: none;
  }

  .course-layout {
    padding-top: 0;
  }

  .course-main {
    margin-left: 0;
  }

  .content-shell {
    width: 100%;
    padding: 0;
  }
}