:root {
  color-scheme: light;
  --bg: #f7f4ed;
  --surface: #fffdf8;
  --surface-2: #ece6da;
  --text: #24201a;
  --muted: #71695d;
  --line: #d9d0c0;
  --accent: #0f766e;
  --accent-2: #b45309;
  --accent-soft: #d6f2ec;
  --code-bg: #efe9dc;
  --shadow: 0 20px 45px rgba(44, 32, 18, 0.10);
  --reader-font: 18px;
}

[data-theme="dark"] {
  color-scheme: dark;
  --bg: #181714;
  --surface: #211f1a;
  --surface-2: #302d26;
  --text: #f1eadc;
  --muted: #b9ad9a;
  --line: #454034;
  --accent: #2dd4bf;
  --accent-2: #f59e0b;
  --accent-soft: rgba(45, 212, 191, 0.16);
  --code-bg: #302d26;
  --shadow: 0 20px 45px rgba(0, 0, 0, 0.26);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  overflow-x: hidden;
  background: var(--bg);
  color: var(--text);
  font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", sans-serif;
}

button,
input {
  font: inherit;
}

.app-shell {
  display: grid;
  grid-template-columns: minmax(280px, 330px) 1fr;
  min-height: 100vh;
}

.sidebar {
  position: sticky;
  top: 0;
  height: 100vh;
  overflow: auto;
  border-right: 1px solid var(--line);
  background: var(--surface);
  padding: 24px 18px;
}

.brand {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 18px;
}

.eyebrow {
  margin: 0 0 6px;
  color: var(--accent);
  font-size: 12px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0;
}

.brand h1 {
  margin: 0;
  font-size: 28px;
  line-height: 1.1;
}

.search-box {
  display: grid;
  grid-template-columns: 24px 1fr;
  align-items: center;
  gap: 8px;
  min-height: 44px;
  margin: 18px 0;
  padding: 0 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--bg);
  color: var(--muted);
}

.search-box input {
  width: 100%;
  min-width: 0;
  border: 0;
  outline: 0;
  background: transparent;
  color: var(--text);
}

.chapter-list {
  display: grid;
  gap: 4px;
}

.chapter-link {
  display: grid;
  grid-template-columns: 36px 1fr;
  gap: 10px;
  align-items: center;
  width: 100%;
  min-height: 46px;
  padding: 8px 10px;
  border: 0;
  border-radius: 8px;
  background: transparent;
  color: var(--text);
  text-align: left;
  cursor: pointer;
}

.chapter-link:hover,
.chapter-link.active {
  background: var(--accent-soft);
}

.chapter-index {
  color: var(--accent-2);
  font-size: 12px;
  font-weight: 800;
}

.chapter-name {
  min-width: 0;
  overflow: hidden;
  font-size: 14px;
  font-weight: 700;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.chapter-count {
  grid-column: 2;
  color: var(--muted);
  font-size: 12px;
}

.reader {
  min-width: 0;
  overflow-x: hidden;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  min-height: 68px;
  padding: 12px 28px;
  border-bottom: 1px solid var(--line);
  background: color-mix(in srgb, var(--surface) 88%, transparent);
  backdrop-filter: blur(16px);
}

.current-meta {
  min-width: 0;
  display: grid;
  gap: 3px;
}

.current-meta span {
  color: var(--muted);
  font-size: 12px;
  font-weight: 800;
  text-transform: uppercase;
}

.current-meta strong {
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.top-actions {
  display: flex;
  gap: 8px;
}

.icon-button {
  display: inline-grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
}

.icon-button:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.progress-track {
  position: sticky;
  top: 68px;
  z-index: 9;
  height: 3px;
  background: transparent;
}

.progress-bar {
  width: 0%;
  height: 100%;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
}

.study-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(220px, 280px);
  align-items: start;
  gap: 32px;
  width: min(1160px, calc(100vw - 330px));
  margin: 0 auto;
  padding: 42px 32px 24px;
}

.content {
  min-width: 0;
  padding: 48px min(7vw, 72px);
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  box-shadow: var(--shadow);
  font-size: var(--reader-font);
  line-height: 1.82;
}

.content h1,
.content h2,
.content h3,
.content h4 {
  line-height: 1.25;
  letter-spacing: 0;
}

.content h1 {
  margin: 0 0 26px;
  font-size: 34px;
}

.content h2 {
  margin: 42px 0 14px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
  font-size: 25px;
}

.content h3 {
  margin: 28px 0 10px;
  color: var(--accent);
  font-size: 20px;
}

.content p,
.content ul,
.content ol,
.content table,
.content blockquote {
  margin: 0 0 18px;
}

.content ul,
.content ol {
  padding-left: 1.4em;
}

.content li + li {
  margin-top: 8px;
}

.content strong {
  color: var(--text);
}

.content code {
  padding: 2px 6px;
  border-radius: 6px;
  background: var(--code-bg);
  color: var(--accent-2);
  font-family: ui-monospace, SFMono-Regular, Consolas, "Liberation Mono", monospace;
  font-size: 0.92em;
}

.math-block {
  overflow-x: auto;
  margin: 18px 0 22px;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--code-bg);
  text-align: center;
}

.math-block mjx-container {
  margin: 0 !important;
  max-width: 100%;
  font-size: 96% !important;
}

.math-block::-webkit-scrollbar,
.content table::-webkit-scrollbar {
  height: 8px;
}

.math-block::-webkit-scrollbar-thumb,
.content table::-webkit-scrollbar-thumb {
  border-radius: 999px;
  background: color-mix(in srgb, var(--muted) 46%, transparent);
}

.content pre {
  overflow: auto;
  padding: 16px;
  border-radius: 8px;
  background: var(--code-bg);
}

.content blockquote {
  padding: 14px 18px;
  border-left: 4px solid var(--accent);
  background: var(--accent-soft);
}

.content table {
  display: block;
  width: 100%;
  overflow-x: auto;
  border-collapse: collapse;
  white-space: nowrap;
}

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

.content th {
  background: var(--surface-2);
}

.content mark {
  border-radius: 4px;
  background: rgba(245, 158, 11, 0.32);
  color: inherit;
}

.page-note {
  color: var(--muted);
  font-size: 14px;
}

.outline-panel {
  position: sticky;
  top: 96px;
  max-height: calc(100vh - 116px);
  overflow: auto;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
}

.outline-title {
  margin-bottom: 12px;
  color: var(--muted);
  font-size: 12px;
  font-weight: 800;
}

.outline-link {
  display: block;
  padding: 7px 0;
  color: var(--muted);
  font-size: 13px;
  line-height: 1.35;
  text-decoration: none;
}

.outline-link:hover {
  color: var(--accent);
}

.outline-link.level-3 {
  padding-left: 14px;
}

.reader-footer {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  width: min(1160px, calc(100vw - 330px));
  margin: 0 auto;
  padding: 8px 32px 48px;
}

.nav-button {
  min-width: 128px;
  min-height: 44px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
}

.nav-button:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.nav-button:disabled {
  cursor: not-allowed;
  opacity: 0.45;
}

.mobile-only {
  display: none;
}

@media (max-width: 1080px) {
  .app-shell {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: fixed;
    inset: 0 auto 0 0;
    z-index: 30;
    width: min(86vw, 340px);
    transform: translateX(-104%);
    transition: transform 180ms ease;
    box-shadow: var(--shadow);
  }

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

  .mobile-only {
    display: inline-grid;
  }

  .study-layout,
  .reader-footer {
    width: min(100%, 920px);
  }

  .study-layout {
    grid-template-columns: 1fr;
  }

  .outline-panel {
    display: none;
  }
}

@media (max-width: 640px) {
  :root {
    --reader-font: 16px;
  }

  .topbar {
    padding: 10px 14px;
  }

  .top-actions {
    gap: 6px;
  }

  .icon-button {
    width: 36px;
    height: 36px;
  }

  .study-layout {
    padding: 18px 12px 14px;
  }

  .content {
    padding: 28px 18px;
  }

  .content h1 {
    font-size: 28px;
  }

  .content h2 {
    font-size: 21px;
  }

  .reader-footer {
    padding: 6px 12px 28px;
  }
}