:root {
  --bg: #f0e5d4;
  --bg-2: #e5cfb4;
  --sidebar: #262220;
  --sidebar-2: #372d27;
  --paper: #fffaf1;
  --paper-edge: #e7d6be;
  --paper-shadow: 0 28px 70px rgba(103, 60, 29, 0.18);
  --ink: #201d1a;
  --muted: #6d655f;
  --line: rgba(32, 29, 26, 0.12);
  --accent: #c96e3d;
  --accent-2: #a84523;
  --accent-soft: rgba(201, 110, 61, 0.13);
  --card-bg: rgba(255, 255, 255, 0.82);
  --card-bg-strong: rgba(255, 255, 255, 0.94);
  --button-secondary-bg: rgba(255, 255, 255, 0.72);
  --button-secondary-hover: rgba(255, 255, 255, 0.9);
  --input-bg: rgba(255, 255, 255, 0.08);
  --input-placeholder: rgba(248, 239, 225, 0.64);
}

html[data-theme="dark"] {
  --bg: #131618;
  --bg-2: #283036;
  --sidebar: #0f1112;
  --sidebar-2: #1c2023;
  --paper: #1b1f23;
  --paper-edge: #323840;
  --paper-shadow: 0 28px 70px rgba(0, 0, 0, 0.45);
  --ink: #eef1f2;
  --muted: #aeb6ba;
  --line: rgba(255, 255, 255, 0.09);
  --accent: #f0a36c;
  --accent-2: #ffcf9c;
  --accent-soft: rgba(240, 163, 108, 0.12);
  --card-bg: rgba(255, 255, 255, 0.04);
  --card-bg-strong: rgba(255, 255, 255, 0.07);
  --button-secondary-bg: rgba(255, 255, 255, 0.06);
  --button-secondary-hover: rgba(255, 255, 255, 0.12);
  --input-bg: rgba(255, 255, 255, 0.06);
  --input-placeholder: rgba(238, 241, 242, 0.52);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  font-family: "IBM Plex Sans TC", sans-serif;
  background:
    radial-gradient(circle at top left, rgba(255, 244, 223, 0.55), transparent 24%),
    radial-gradient(circle at bottom right, rgba(201, 110, 61, 0.16), transparent 26%),
    linear-gradient(135deg, var(--bg) 0%, var(--bg-2) 100%);
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  background:
    linear-gradient(rgba(255, 255, 255, 0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.04) 1px, transparent 1px);
  background-size: 24px 24px;
  mask-image: radial-gradient(circle at center, black 32%, transparent 88%);
}

.book-layout {
  min-height: 100vh;
  display: grid;
  grid-template-columns: 320px minmax(0, 1fr);
}

.book-sidebar {
  position: sticky;
  top: 0;
  height: 100vh;
  padding: 24px 0 24px 24px;
}

.sidebar-panel {
  height: 100%;
  padding: 24px 20px;
  border-radius: 28px 0 0 28px;
  color: #f8efe1;
  background: linear-gradient(135deg, var(--sidebar) 0%, var(--sidebar-2) 100%);
  box-shadow: inset -1px 0 0 rgba(255, 255, 255, 0.06);
  display: flex;
  flex-direction: column;
}

.eyebrow,
.chapter-number {
  margin: 0 0 10px;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  font-size: 0.76rem;
}

.eyebrow {
  color: rgba(248, 239, 225, 0.72);
}

.eyebrow.warm {
  color: var(--accent);
}

h1,
h2,
h3,
h4 {
  font-family: "Noto Serif TC", serif;
}

.sidebar-panel h1 {
  margin: 0;
  font-size: 2rem;
  line-height: 1.2;
}

.subtitle {
  margin: 14px 0 18px;
  line-height: 1.7;
  color: rgba(248, 239, 225, 0.78);
}

.search-box {
  display: grid;
  gap: 8px;
  font-size: 0.92rem;
  color: rgba(248, 239, 225, 0.8);
}

.search-box input {
  width: 100%;
  border: 1px solid rgba(255, 255, 255, 0.12);
  background: var(--input-bg);
  color: #fff7ed;
  border-radius: 14px;
  padding: 12px 14px;
  font: inherit;
}

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

.toc {
  margin-top: 18px;
  display: grid;
  gap: 8px;
}

.toc a {
  color: rgba(248, 239, 225, 0.9);
  text-decoration: none;
  padding: 11px 12px;
  border-radius: 12px;
  border: 1px solid transparent;
  transition: transform 180ms ease, background-color 180ms ease, border-color 180ms ease;
}

.toc a:hover,
.toc a.is-active {
  transform: translateX(4px);
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.12);
}

.toc a.is-hidden {
  display: none;
}

.sidebar-actions {
  margin-top: auto;
  display: grid;
  gap: 10px;
}

.toolbar-button {
  border: 0;
  border-radius: 999px;
  padding: 12px 16px;
  font: inherit;
  font-weight: 700;
  cursor: pointer;
  color: #241812;
  background: linear-gradient(135deg, #ffd7b0, #db8353);
}

.book-main {
  padding: 24px 24px 24px 0;
  display: flex;
  align-items: flex-start;
  justify-content: center;
}

.page-card {
  position: relative;
  width: min(980px, 100%);
  max-width: 980px;
  min-height: calc(100vh - 48px);
  padding: 42px;
  border-radius: 0 28px 28px 0;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.08), transparent 10%), var(--paper);
  box-shadow: var(--paper-shadow);
  border: 1px solid var(--line);
  overflow: hidden;
}

.page-card::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 22px;
  background:
    linear-gradient(90deg, rgba(0, 0, 0, 0.08), transparent),
    linear-gradient(180deg, var(--paper-edge), transparent 15%, transparent 85%, var(--paper-edge));
}

.page-card::after {
  content: "";
  position: absolute;
  right: 14px;
  top: 18px;
  bottom: 18px;
  width: 8px;
  border-radius: 999px;
  background: linear-gradient(180deg, rgba(0, 0, 0, 0.05), rgba(255, 255, 255, 0.12), rgba(0, 0, 0, 0.08));
  opacity: 0.42;
}

.page-flourish {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    radial-gradient(circle at top right, rgba(201, 110, 61, 0.18), transparent 22%),
    radial-gradient(circle at 15% 82%, rgba(70, 95, 88, 0.12), transparent 18%);
}

.page-card,
.page-card h2,
.page-card h3,
.page-card h4,
.page-card p,
.page-card li,
.page-card strong,
.page-card code,
.comparison-table th,
.comparison-table td {
  color: var(--ink);
}

.cover-page {
  display: grid;
  gap: 34px;
}

.cover-grid {
  position: relative;
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 24px;
  align-items: center;
}

.cover-copy h2,
.chapter-header h2 {
  margin: 0 0 18px;
  font-size: clamp(2.2rem, 3.8vw, 4.2rem);
  line-height: 1.12;
}

.cover-copy p,
.page-card p,
.page-card li {
  line-height: 1.85;
  font-size: 1.02rem;
}

.cover-figure {
  margin: 0;
  padding: 18px;
  border-radius: 28px;
  background: var(--card-bg-strong);
  border: 1px solid var(--line);
}

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

.feature-strip,
.info-grid,
.intro-columns,
.command-grid,
.timeline {
  display: grid;
  gap: 18px;
}

.feature-strip {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.intro-columns,
.info-grid.two {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.info-grid.three,
.command-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.feature-strip article,
.info-card,
.command-card,
.practice-block,
.section-block,
.timeline article,
.comparison-table,
pre,
.callout {
  position: relative;
  z-index: 1;
  border: 1px solid var(--line);
  border-radius: 22px;
  background: var(--card-bg-strong);
  padding: 20px;
}

html[data-theme="dark"] .cover-figure,
html[data-theme="dark"] .feature-strip article,
html[data-theme="dark"] .info-card,
html[data-theme="dark"] .command-card,
html[data-theme="dark"] .practice-block,
html[data-theme="dark"] .section-block,
html[data-theme="dark"] .timeline article,
html[data-theme="dark"] .comparison-table,
html[data-theme="dark"] pre,
html[data-theme="dark"] .callout {
  background: var(--card-bg-strong);
}

.feature-strip h3,
.info-card h3,
.info-card h4,
.section-block h3,
.practice-block h3,
.command-card code {
  margin-top: 0;
}

.feature-strip article p,
.info-card p,
.command-card p,
.practice-block p,
.section-block p,
.timeline article p,
.comparison-table th,
.comparison-table td {
  overflow-wrap: anywhere;
}

.action-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 0 18px;
  border-radius: 999px;
  font-weight: 700;
  text-decoration: none;
}

.button.primary {
  color: #fff8ef;
  background: linear-gradient(135deg, var(--accent-2), var(--accent));
}

.button.secondary {
  color: var(--ink);
  border: 1px solid var(--line);
  background: var(--button-secondary-bg);
}

.button.secondary:hover {
  background: var(--button-secondary-hover);
}

.plain-list,
.steps {
  padding-left: 22px;
}

pre {
  overflow-x: auto;
}

code {
  font-family: "JetBrains Mono", monospace;
  font-size: 0.95em;
}

pre code {
  display: block;
  white-space: pre-wrap;
  line-height: 1.8;
}

.chapter-header {
  margin-bottom: 26px;
  padding-bottom: 18px;
  border-bottom: 1px solid var(--line);
}

.chapter-number {
  color: var(--accent);
}

.callout {
  border-left: 6px solid var(--accent);
}

.callout.soft {
  background: var(--accent-soft);
}

.command-card code {
  display: inline-block;
  margin-bottom: 8px;
  font-size: 1rem;
}

.timeline article span {
  display: inline-block;
  margin-bottom: 8px;
  font-weight: 700;
  color: var(--accent);
}

.comparison-table-wrap {
  overflow-x: auto;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: var(--card-bg-strong);
}

.comparison-table {
  width: 100%;
  border-collapse: collapse;
  min-width: 520px;
}

.comparison-table th,
.comparison-table td {
  padding: 16px 18px;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--line);
}

.comparison-table th:not(:last-child),
.comparison-table td:not(:last-child) {
  border-right: 1px solid var(--line);
}

.comparison-table thead th {
  background: var(--accent-soft);
  font-weight: 700;
}

.comparison-table tbody th {
  width: 28%;
  font-weight: 700;
  background: rgba(0, 0, 0, 0.02);
}

html[data-theme="dark"] .comparison-table tbody th {
  background: rgba(255, 255, 255, 0.04);
}

.comparison-table tbody tr:last-child th,
.comparison-table tbody tr:last-child td {
  border-bottom: 0;
}

.page-nav {
  margin-top: 28px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.page-nav a,
.page-hint {
  color: var(--accent-2);
  text-decoration: none;
  font-weight: 700;
}

.page-nav a:hover,
.toc a:hover,
.button:hover,
.toolbar-button:hover {
  filter: brightness(1.04);
}

.exercise-set {
  display: grid;
  gap: 18px;
}

.exercise-item {
  border: 1px solid var(--line);
  border-radius: 18px;
  background: var(--card-bg);
  padding: 18px;
}

.exercise-item h4,
.answer-block h5 {
  margin-top: 0;
}

.answer-block {
  margin-top: 14px;
  padding-top: 14px;
  border-top: 1px dashed var(--line);
}

.answer-block h5 {
  margin-bottom: 8px;
  color: var(--accent-2);
  font-size: 0.96rem;
}

.answer-block p:last-child {
  margin-bottom: 0;
}

@media (max-width: 1100px) {
  .book-layout {
    grid-template-columns: 1fr;
  }

  .book-sidebar {
    position: relative;
    height: auto;
    padding: 20px 20px 0;
  }

  .sidebar-panel {
    border-radius: 28px;
  }

  .book-main {
    padding: 20px;
  }

  .page-card {
    width: 100%;
    min-height: auto;
    border-radius: 28px;
  }
}

@media (max-width: 980px) {
  .feature-strip,
  .info-grid.three,
  .command-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

@media (max-width: 760px) {
  .page-card {
    padding: 22px;
    border-radius: 22px;
  }

  .book-main {
    padding: 16px;
  }

  .sidebar-panel {
    border-radius: 22px;
  }

  .cover-grid,
  .feature-strip,
  .intro-columns,
  .info-grid.two,
  .info-grid.three,
  .command-grid {
    grid-template-columns: 1fr;
  }

  .cover-copy h2,
  .chapter-header h2 {
    font-size: 2.25rem;
  }

  .page-nav {
    flex-direction: column;
    align-items: flex-start;
  }

  .page-card::before,
  .page-card::after {
    display: none;
  }
}

@media print {
  body {
    background: white;
  }

  body::before,
  .book-sidebar,
  .page-card::before,
  .page-card::after,
  .page-flourish,
  .sidebar-actions {
    display: none !important;
  }

  .book-layout,
  .book-main {
    display: block;
    padding: 0;
  }

  .page-card {
    width: auto;
    min-height: auto;
    border: 0;
    box-shadow: none;
    border-radius: 0;
    background: white;
    padding: 0;
  }

  .page-nav {
    display: none;
  }

  a {
    color: black;
    text-decoration: none;
  }

  @page {
    size: A4;
    margin: 16mm;
  }
}