:root {
  color-scheme: light;
  --paper: #f8f5ee;
  --paper-raised: #fffdf8;
  --paper-deep: #ede8dc;
  --ink: #1d211f;
  --ink-soft: #5d635e;
  --ink-faint: #8b8f89;
  --line: #ddd7ca;
  --accent: #c4512c;
  --accent-deep: #8d3118;
  --accent-wash: #f4ded2;
  --green: #496a5a;
  --sidebar-width: 304px;
  --outline-width: 220px;
  font-family: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI",
    "PingFang SC", "Microsoft YaHei", sans-serif;
  font-synthesis: none;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  min-width: 1080px;
  background: var(--paper);
  color: var(--ink);
  font-size: 15px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

button, input { font: inherit; }
button { color: inherit; }

.skip-link {
  position: fixed;
  left: 50%;
  top: -60px;
  z-index: 100;
  padding: 10px 18px;
  border-radius: 8px;
  background: var(--ink);
  color: white;
  transition: top 150ms ease;
}

.skip-link:focus { top: 12px; }

.reader-shell { min-height: 100vh; }

.book-sidebar {
  position: fixed;
  inset: 0 auto 0 0;
  z-index: 10;
  display: flex;
  width: var(--sidebar-width);
  flex-direction: column;
  border-right: 1px solid var(--line);
  background:
    radial-gradient(circle at 20px 20px, rgb(196 81 44 / 5%) 1px, transparent 1px) 0 0 / 18px 18px,
    var(--paper-raised);
}

.book-brand { padding: 30px 26px 20px; }

.brand-kicker {
  display: block;
  margin-bottom: 10px;
  color: var(--accent);
  font: 700 10px/1.2 ui-monospace, SFMono-Regular, Menlo, monospace;
  letter-spacing: 0.16em;
}

.brand-title {
  display: block;
  color: var(--ink);
  font-family: ui-serif, "Songti SC", "STSong", serif;
  font-size: 22px;
  font-weight: 800;
  line-height: 1.3;
  text-decoration: none;
}

.book-brand p {
  margin: 10px 0 0;
  color: var(--ink-soft);
  font-size: 12px;
  line-height: 1.6;
}

.book-progress {
  margin: 0 20px 16px;
  padding: 12px 14px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: rgb(255 255 255 / 55%);
}

.book-progress > div:first-child {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  color: var(--ink-soft);
  font-size: 11px;
}

.book-progress strong { color: var(--ink); font-size: 12px; }

.progress-track {
  height: 4px;
  margin-top: 9px;
  overflow: hidden;
  border-radius: 999px;
  background: var(--paper-deep);
}

.progress-track span {
  display: block;
  width: 0;
  height: 100%;
  border-radius: inherit;
  background: var(--accent);
  transition: width 300ms ease;
}

.book-navigation {
  flex: 1;
  overflow: auto;
  padding: 0 14px 28px;
  scrollbar-width: thin;
  scrollbar-color: var(--line) transparent;
}

.navigation-section { margin: 18px 0 0; }

.navigation-section h2 {
  margin: 0 10px 8px;
  color: var(--ink-faint);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.chapter-link {
  display: grid;
  width: 100%;
  grid-template-columns: 25px minmax(0, 1fr);
  align-items: start;
  gap: 7px;
  margin: 1px 0;
  padding: 7px 10px;
  border: 0;
  border-radius: 7px;
  background: transparent;
  text-align: left;
}

button.chapter-link { cursor: pointer; }
button.chapter-link:hover { background: var(--paper-deep); }

.chapter-link.is-active {
  background: var(--accent-wash);
  color: var(--accent-deep);
  font-weight: 650;
}

.chapter-number {
  color: var(--ink-faint);
  font: 600 11px/1.8 ui-monospace, SFMono-Regular, Menlo, monospace;
}

.chapter-link > span:nth-child(2) { font-size: 12px; line-height: 1.65; }

.chapter-link.unavailable {
  position: relative;
  grid-template-columns: 25px minmax(0, 1fr) auto;
  color: var(--ink-faint);
}

.chapter-link.unavailable small {
  margin-top: 1px;
  padding: 0 5px;
  border: 1px solid var(--line);
  border-radius: 4px;
  font-size: 9px;
  line-height: 1.7;
}

.introduction-link { margin-bottom: 12px; }

.navigation-loading, .navigation-error {
  padding: 16px 12px;
  color: var(--ink-faint);
  font-size: 12px;
}

.sidebar-footer {
  display: flex;
  align-items: center;
  gap: 8px;
  min-height: 48px;
  padding: 0 24px;
  border-top: 1px solid var(--line);
  color: var(--ink-faint);
  font-size: 11px;
}

.sidebar-footer kbd {
  margin-left: auto;
  padding: 1px 6px;
  border: 1px solid var(--line);
  border-bottom-width: 2px;
  border-radius: 5px;
  background: var(--paper);
  font-size: 10px;
}

.local-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: #4a8b65;
  box-shadow: 0 0 0 3px rgb(74 139 101 / 12%);
}

.reader-main { margin-left: var(--sidebar-width); }

.reader-toolbar {
  position: sticky;
  top: 0;
  z-index: 8;
  display: flex;
  height: 68px;
  align-items: center;
  justify-content: space-between;
  padding: 0 34px;
  border-bottom: 1px solid var(--line);
  background: rgb(248 245 238 / 92%);
  backdrop-filter: blur(18px);
}

.reader-toolbar > div:first-child { display: flex; flex-direction: column; min-width: 0; }
.reader-toolbar strong { overflow: hidden; font-size: 13px; text-overflow: ellipsis; white-space: nowrap; }

.chapter-eyebrow {
  color: var(--accent);
  font: 700 9px/1.5 ui-monospace, SFMono-Regular, Menlo, monospace;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.toolbar-actions { display: flex; align-items: center; gap: 16px; }

.toolbar-button {
  padding: 6px 10px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--paper-raised);
  color: var(--ink-soft);
  cursor: pointer;
  font-size: 11px;
}

.toolbar-button:hover { border-color: #bbb2a2; color: var(--ink); }

.reading-state { color: var(--ink-faint); font-size: 10px; }

.reader-grid {
  display: grid;
  grid-template-columns: minmax(580px, 860px) var(--outline-width);
  justify-content: center;
  gap: 72px;
  padding: 76px 48px 42px;
}

.book-content {
  width: 100%;
  min-height: calc(100vh - 180px);
  outline: none;
  font-family: ui-serif, Georgia, "Songti SC", "STSong", serif;
  font-size: 17px;
  line-height: 1.92;
}

.book-content > :first-child { margin-top: 0; }

.book-content h1,
.book-content h2,
.book-content h3,
.book-content h4 {
  color: #171a18;
  font-family: ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", sans-serif;
  line-height: 1.35;
  scroll-margin-top: 94px;
}

.book-content h1 {
  max-width: 760px;
  margin: 0 0 42px;
  font-size: clamp(36px, 4.1vw, 58px);
  font-weight: 820;
  letter-spacing: -0.045em;
}

.book-content h1::after {
  display: block;
  width: 52px;
  height: 5px;
  margin-top: 22px;
  background: var(--accent);
  content: "";
}

.book-content h2 {
  margin: 72px 0 22px;
  padding-top: 12px;
  border-top: 1px solid var(--line);
  font-size: 27px;
  letter-spacing: -0.025em;
}

.book-content h3 { margin: 44px 0 16px; font-size: 20px; }
.book-content h4 { margin: 32px 0 12px; font-size: 16px; }

.book-content p { margin: 0 0 22px; }

.book-content a {
  color: var(--accent-deep);
  text-decoration-color: rgb(141 49 24 / 35%);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

.book-content a:hover { text-decoration-color: var(--accent-deep); }

.book-content .unavailable-link {
  color: var(--ink-faint);
  cursor: not-allowed;
  text-decoration-style: dotted;
}

.book-content strong { font-weight: 750; }

.book-content ul, .book-content ol { margin: 0 0 24px; padding-left: 1.5em; }
.book-content li { margin: 8px 0; padding-left: 0.25em; }
.book-content li::marker { color: var(--accent); }

.book-content blockquote {
  margin: 32px 0;
  padding: 4px 0 4px 24px;
  border-left: 4px solid var(--accent);
  color: var(--ink-soft);
  font-size: 18px;
}

.book-content blockquote > :last-child { margin-bottom: 0; }

.book-content :not(pre) > code {
  padding: 0.13em 0.36em;
  border: 1px solid #dfd8c9;
  border-radius: 4px;
  background: #f0ebe1;
  color: #71321f;
  font: 0.84em/1.4 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

.code-shell {
  margin: 30px 0;
  overflow: hidden;
  border: 1px solid #d7d0c2;
  border-radius: 9px;
  background: #f6f3ec;
  box-shadow: 0 8px 30px rgb(42 37 27 / 5%);
}

.code-toolbar {
  display: flex;
  min-height: 34px;
  align-items: center;
  justify-content: space-between;
  padding: 0 12px 0 15px;
  border-bottom: 1px solid #d7d0c2;
  color: var(--ink-faint);
  font: 600 10px/1 ui-monospace, SFMono-Regular, Menlo, monospace;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.code-toolbar button {
  padding: 4px 7px;
  border: 0;
  border-radius: 4px;
  background: transparent;
  color: var(--ink-soft);
  cursor: pointer;
  font-size: 10px;
}

.code-toolbar button:hover { background: var(--paper-deep); }

.code-shell pre {
  margin: 0;
  overflow: auto;
  padding: 19px 21px;
  background: transparent;
}

.code-shell code,
.code-shell .hljs {
  padding: 0;
  background: transparent;
  font: 13px/1.7 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

.table-scroll { margin: 30px 0; overflow-x: auto; }

.book-content table {
  width: 100%;
  border-collapse: collapse;
  font-family: ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", sans-serif;
  font-size: 13px;
}

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

.book-content th { background: var(--paper-deep); font-weight: 700; }

.mermaid-diagram {
  margin: 38px 0;
  overflow: auto;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--paper-raised);
  text-align: center;
}

.mermaid-diagram svg { display: block; max-width: 100%; height: auto; margin: auto; }

.mermaid-diagram.diagram-error { color: var(--accent-deep); text-align: left; }
.mermaid-diagram.diagram-error strong { font-family: ui-sans-serif, sans-serif; }
.mermaid-diagram.diagram-error pre { white-space: pre-wrap; }

.page-outline { min-width: 0; }

.outline-inner {
  position: sticky;
  top: 102px;
  max-height: calc(100vh - 134px);
  overflow: auto;
  padding-left: 18px;
  border-left: 1px solid var(--line);
}

.outline-inner > strong {
  display: block;
  margin-bottom: 12px;
  color: var(--ink-soft);
  font-size: 11px;
}

.outline-inner nav { display: flex; flex-direction: column; gap: 7px; }

.outline-inner a {
  overflow: hidden;
  color: var(--ink-faint);
  font-size: 11px;
  line-height: 1.5;
  text-decoration: none;
  text-overflow: ellipsis;
}

.outline-inner a:hover { color: var(--accent-deep); }
.outline-inner a.outline-level-3 { padding-left: 12px; font-size: 10px; }
.outline-empty { color: var(--ink-faint); font-size: 11px; }

.chapter-pagination {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 20px;
  max-width: 1152px;
  margin: 0 auto;
  padding: 26px 48px 70px;
  border-top: 1px solid var(--line);
}

.pagination-button {
  display: flex;
  min-height: 76px;
  flex-direction: column;
  justify-content: center;
  padding: 12px 18px;
  border: 1px solid var(--line);
  border-radius: 9px;
  background: var(--paper-raised);
  cursor: pointer;
  text-align: left;
}

.pagination-button.next { align-items: flex-end; text-align: right; }
.pagination-button:hover { border-color: #c4b9a6; transform: translateY(-1px); }
.pagination-button small { color: var(--ink-faint); font-size: 10px; }
.pagination-button strong { margin-top: 3px; font-size: 12px; }

.content-loading {
  display: flex;
  min-height: 50vh;
  align-items: center;
  justify-content: center;
  gap: 12px;
  color: var(--ink-faint);
  font-family: ui-sans-serif, sans-serif;
  font-size: 12px;
}

.loading-mark {
  width: 12px;
  height: 12px;
  border: 2px solid var(--line);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 700ms linear infinite;
}

@keyframes spin { to { transform: rotate(360deg); } }

.reader-error {
  padding: 60px 0;
  font-family: ui-sans-serif, sans-serif;
}

.reader-error > span { color: var(--accent); font: 700 10px ui-monospace, monospace; }
.reader-error h1 { margin: 14px 0; font-size: 38px; }
.reader-error p { color: var(--ink-soft); }
.reader-error button {
  padding: 8px 14px;
  border: 0;
  border-radius: 6px;
  background: var(--ink);
  color: white;
  cursor: pointer;
}

.command-dialog {
  width: min(620px, calc(100vw - 80px));
  margin-top: 12vh;
  padding: 0;
  border: 1px solid #cfc7b8;
  border-radius: 12px;
  background: var(--paper-raised);
  box-shadow: 0 24px 80px rgb(27 24 18 / 24%);
}

.command-dialog::backdrop { background: rgb(32 29 23 / 38%); backdrop-filter: blur(4px); }
.command-shell { padding: 0; }

.command-shell header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 15px 18px 8px;
}

.command-shell label { color: var(--ink-soft); font-size: 11px; font-weight: 700; }
.command-shell header button { border: 0; background: transparent; color: var(--ink-faint); font-size: 10px; }

.command-shell input {
  width: calc(100% - 36px);
  margin: 0 18px 12px;
  padding: 12px 13px;
  border: 1px solid var(--line);
  border-radius: 8px;
  outline: none;
  background: var(--paper);
}

.command-shell input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px rgb(196 81 44 / 10%); }

.command-results { max-height: 440px; overflow: auto; padding: 4px 10px 12px; }

.command-results button {
  display: flex;
  width: 100%;
  align-items: center;
  justify-content: space-between;
  padding: 10px 11px;
  border: 0;
  border-radius: 7px;
  background: transparent;
  cursor: pointer;
  text-align: left;
}

.command-results button:hover { background: var(--paper-deep); }
.command-results button span { font-size: 13px; }
.command-results button small { color: var(--ink-faint); font-size: 10px; }
.command-results > p { padding: 24px; color: var(--ink-faint); text-align: center; }

@media print {
  body { min-width: 0; background: white; }
  .book-sidebar, .reader-toolbar, .page-outline, .chapter-pagination { display: none; }
  .reader-main { margin: 0; }
  .reader-grid { display: block; padding: 0; }
  .book-content { font-size: 11pt; }
}