:root {
  /* Backgrounds — Anthropic-inspired warm neutrals */
  --bg-dark: #1a1915;
  --bg-dark-soft: #252320;
  --bg-paper: #edeae2;
  --bg-page: #faf9f6;
  --bg-page-soft: #f5f3ed;

  /* Text — warm dark scale */
  --text-strong: #2c2b25;
  --text-body: #4e4a40;
  --text-soft: #6b6858;

  /* Lines — lighter, subtler */
  --line: #e5e2d9;
  --line-strong: #d4d0c6;

  /* Accents — refined earth tones */
  --accent: #a85b2f;
  --accent-dark: #8a4a24;
  --accent-warm: #c2634a;
  --accent-olive: #6b8258;
  --accent-blue: #5b7693;
  --accent-border-blue: #b4c6d4;
  --accent-border-purple: #c5bfd9;
  --accent-border-green: #b5c5c0;

  /* Code */
  --code-bg: #1a1915;
  --code-text: #e8d5b0;

  /* Shadows — subtler */
  --shadow-page: 0 4px 24px rgba(0, 0, 0, 0.06);

  /* Radii */
  --radius-lg: 12px;
  --radius-md: 8px;
  --radius-sm: 6px;

  /* Typography */
  --font-display: "Source Serif 4", "Noto Serif SC", "Source Han Serif SC", serif;
  --font-body: "Inter", "IBM Plex Sans", "PingFang SC", "Noto Sans SC", sans-serif;
  --font-mono: "JetBrains Mono", "IBM Plex Mono", monospace;

  /* Spacing rhythm */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-normal: 0.2s ease;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

/* Skip-to-content link (accessibility) */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-md);
  z-index: 9999;
  padding: var(--space-sm) var(--space-md);
  background: var(--accent);
  color: #fff;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  font-weight: 500;
  text-decoration: none;
  transition: top var(--transition-fast);
}
.skip-link:focus {
  top: var(--space-sm);
}

body {
  font-family: var(--font-body);
  color: var(--text-strong);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

a {
  color: inherit;
}

.site-brand__mark {
  width: 38px;
  height: 38px;
  color: var(--accent-warm);
  flex: 0 0 auto;
}

body.page-doc-book {
  background: var(--bg-paper);
  color: var(--text-strong);
  padding: 28px 18px 72px;
}

.book-shell {
  max-width: 1220px;
  margin: 0 auto;
}

.book-topline {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  align-items: center;
  margin-bottom: 18px;
  padding: 0 10px;
}

.book-topline__brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
}

.book-topline__brand .site-brand__mark {
  width: 28px;
  height: 28px;
  color: var(--accent-dark);
}

.book-topline__name {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-strong);
}

.book-topline__tag {
  color: var(--text-soft);
  font-size: 0.72rem;
  margin-top: 2px;
}

.book-topline__nav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  justify-content: flex-end;
}

.book-pill-nav {
  display: inline-flex;
  align-items: center;
  padding: 7px 14px;
  border-radius: 999px;
  background: rgba(250, 249, 246, 0.8);
  border: 1px solid var(--line);
  color: var(--text-soft);
  text-decoration: none;
  font-size: 0.78rem;
  font-weight: 500;
  line-height: 1;
  transition: transform var(--transition-fast),
              border-color var(--transition-fast),
              color var(--transition-fast),
              background var(--transition-fast);
}

.book-pill-nav:hover,
.book-pill-nav.is-active {
  transform: translateY(-1px);
  border-color: var(--accent);
  color: var(--accent-dark);
  background: rgba(168, 91, 47, 0.06);
}

.book-pill-nav:focus-visible,
.toc-row:focus-visible,
.copy-btn:focus-visible,
.doc-content details summary:focus-visible,
.doc-content .tab-btn:focus-visible,
.chapter-nav__link:focus-visible,
.back-to-top:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.book {
  max-width: 1200px;
  margin: 0 auto;
  padding: 12px 10px 0;
}

.page {
  width: 1100px;
  max-width: 100%;
  min-height: 820px;
  margin: 0 auto 28px;
  background: var(--bg-page);
  position: relative;
  padding: 56px 72px 52px;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-page);
  overflow: hidden;
  transition: box-shadow var(--transition-normal);
}

.page-num {
  position: absolute;
  bottom: 28px;
  right: 72px;
  font-size: 12px;
  color: var(--text-soft);
  font-family: var(--font-mono);
}

.page-cover {
  padding: 0;
  min-height: 580px;
  position: relative;
}

/* Dark scrim overlay — ensures white text passes AA on all gradient stops */
.page-cover::before {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.25);
  z-index: 0;
  pointer-events: none;
}

.page-cover__inner {
  position: relative;
  z-index: 1;
  min-height: 580px;
  padding: 56px 72px 48px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.page-cover--warm {
  background: linear-gradient(180deg, #c2634a 0%, #b4563e 100%);
}

.page-cover--olive {
  background: linear-gradient(180deg, #6e8a5c 0%, #5a7348 100%);
}

.page-cover__eyebrow {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: rgba(255, 255, 255, 0.88);
}

.page-cover__title {
  font-family: var(--font-display);
  font-size: clamp(3.2rem, 7vw, 4.9rem);
  line-height: 0.98;
  letter-spacing: -0.03em;
  color: #fff;
  font-weight: 500;
  max-width: 760px;
  text-wrap: balance;
}

.page-cover__summary {
  max-width: 680px;
  color: rgba(255, 255, 255, 0.92);
  font-size: 1.02rem;
  line-height: 1.82;
  text-wrap: pretty;
}

.page-cover__footer {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  gap: 18px;
}

.page-cover__brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
}

.page-cover__brand .site-brand__mark {
  width: 54px;
  height: 54px;
  color: #fff;
}

.page-cover__brand-name {
  font-family: var(--font-display);
  font-size: 1.45rem;
  font-weight: 600;
  color: #fff;
}

.page-cover__brand-sub {
  color: rgba(255, 255, 255, 0.80);
  font-size: 0.78rem;
  margin-top: 2px;
}

.page-cover__meta {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: rgba(255, 255, 255, 0.85);
  text-align: right;
  line-height: 1.8;
}

.pill {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  border: 1.5px solid var(--text-strong);
  border-radius: 999px;
  padding: 5px 14px;
  font-size: 12px;
  font-family: var(--font-mono);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 16px;
  color: var(--text-strong);
  transition: transform var(--transition-fast);
}

.page-title {
  font-family: var(--font-display);
  font-size: 3.2rem;
  line-height: 1.02;
  font-weight: 500;
  color: var(--text-strong);
  margin-bottom: 24px;
  text-wrap: balance;
}

.page-intro {
  font-size: 0.98rem;
  line-height: 1.8;
  color: var(--text-body);
  max-width: 72ch;
  margin-bottom: 18px;
  text-wrap: pretty;
}

.meta-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  margin-top: 20px;
}

.meta-box {
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 14px 16px;
  background: var(--bg-page-soft);
  transition: border-color var(--transition-fast);
}

.meta-box:hover {
  border-color: var(--line-strong);
}

.meta-box--stacked {
  margin-top: 18px;
}

.meta-box__label {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 8px;
}

.meta-box__value {
  color: var(--text-body);
  font-size: 0.88rem;
  line-height: 1.65;
}

.toc-list {
  margin-top: 22px;
  display: grid;
  gap: 10px;
}

.toc-row {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  align-items: baseline;
  text-decoration: none;
  color: inherit;
  padding: 6px 8px;
  margin: 0 -8px;
  border-radius: var(--radius-sm);
  transition: background var(--transition-fast), color var(--transition-fast);
}

.toc-row:hover {
  background: var(--bg-page-soft);
}

.toc-row:hover .toc-row__label {
  color: var(--accent-dark);
}

.toc-row__label {
  font-size: 0.92rem;
  line-height: 1.6;
  color: var(--text-body);
  transition: color var(--transition-fast);
  text-wrap: balance;
}

.toc-row__meta {
  display: inline-block;
  margin-top: 4px;
  font-size: 12px;
  color: var(--text-soft);
}

.toc-row__dots {
  flex: 1;
  border-bottom: 1.5px dotted #c5bbb0;
  margin: 0 8px 4px;
}

.toc-row__page {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-soft);
}

.chapter-page {
  display: grid;
  gap: 16px;
}

.chapter-page__header {
  border-bottom: 1px solid var(--line);
  padding-bottom: 14px;
  margin-bottom: 2px;
}

.chapter-page__eyebrow {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 10px;
}

.chapter-page__title {
  font-family: var(--font-display);
  font-size: 2.1rem;
  line-height: 1.08;
  font-weight: 600;
  color: var(--text-strong);
  margin-bottom: 10px;
  text-wrap: balance;
}

.chapter-page__summary {
  color: var(--text-soft);
  font-size: 0.92rem;
  line-height: 1.72;
  text-wrap: pretty;
}

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

.doc-content > * + * {
  margin-top: 1rem;
}

.doc-content p,
.doc-content li {
  font-size: 0.96rem;
  line-height: 1.82;
  color: var(--text-body);
}

.doc-content p {
  margin-bottom: 0.88rem;
}

.doc-content ul,
.doc-content ol {
  margin: 0.2rem 0 1.08rem 1.25rem;
}

.doc-content a {
  color: var(--accent-dark);
}

.doc-content .dead-link {
  color: var(--text-body);
  border-bottom: 1px dashed var(--line-strong);
  cursor: default;
}

.doc-content h1,
.doc-content h2,
.doc-content h3,
.doc-content h4,
.doc-content .section-title,
.doc-content .ptitle {
  font-family: var(--font-display);
  color: var(--text-strong);
  line-height: 1.16;
  letter-spacing: -0.02em;
  text-wrap: balance;
}

.doc-content h1,
.doc-content .ptitle {
  font-size: clamp(2rem, 3vw, 3rem) !important;
  margin: 0 0 1rem;
  font-weight: 500;
}

.doc-content h2,
.doc-content .section-title {
  font-size: clamp(1.4rem, 2vw, 2rem) !important;
  margin: 2.1rem 0 0.75rem;
  font-weight: 600;
}

.doc-content h3,
.doc-content h4 {
  font-size: 1.06rem !important;
  margin: 1.45rem 0 0.48rem;
  font-weight: 600;
}

.doc-content .ch-num,
.doc-content .ch-subtitle,
.doc-content .section-label,
.doc-content .chapter-label {
  font-family: var(--font-mono) !important;
  font-size: 0.68rem !important;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent) !important;
}

.doc-content .chapter,
.doc-content .content-section {
  margin-bottom: 2.6rem;
}

.doc-content .ch-header,
.doc-content .chapter-header,
.doc-content .section-label {
  border-bottom: 1px solid var(--line);
  padding-bottom: 0.55rem;
}

.doc-content .callout,
.doc-content .rule-box,
.doc-content .exercise-block,
.doc-content .u-card,
.doc-content .lesson-card,
.doc-content .notebox,
.doc-content .ptb,
.doc-content .solbox,
.doc-content .strategy-item,
.doc-content .concept-item,
.doc-content .eval-component {
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 16px 18px 15px;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.doc-content .u-card:hover,
.doc-content .lesson-card:hover,
.doc-content .strategy-item:hover,
.doc-content .concept-item:hover {
  border-color: var(--line-strong);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
}

.doc-content .lesson-card + .lesson-card,
.doc-content .exercise-block + .exercise-block,
.doc-content .callout + .callout {
  margin-top: 1rem;
}

.doc-content .u-grid,
.doc-content .strategy-grid,
.doc-content .concept-grid,
.doc-content .tag-list,
.doc-content .eval-component-grid {
  display: grid;
  gap: 14px;
}

.doc-content .u-grid,
.doc-content .strategy-grid,
.doc-content .concept-grid,
.doc-content .eval-component-grid {
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  margin: 1.15rem 0;
}

.doc-content .tag-list {
  grid-template-columns: repeat(auto-fit, minmax(140px, max-content));
}

.doc-content .tag,
.doc-content .ex-num {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 6px 10px;
  border-radius: 999px;
  background: rgba(168, 91, 47, 0.07);
  border: 1px solid rgba(168, 91, 47, 0.13);
  color: var(--accent-dark);
  font-size: 0.74rem !important;
  line-height: 1;
}

.doc-content .tag,
.doc-content .lesson-tags {
  font-family: var(--font-body);
}

.doc-content .u-kicker,
.doc-content .chapter-en-title,
.doc-content .ec-label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent-dark);
}

.doc-content .u-meta-row,
.doc-content .lesson-header,
.doc-content .ex-header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin-bottom: 0.88rem;
}

.doc-content .pa-item {
  display: grid;
  grid-template-columns: 120px minmax(0, 1fr);
  gap: 16px;
  padding: 14px 0;
  border-bottom: 1px solid var(--line);
}

.doc-content .pa-item:last-child {
  border-bottom: none;
}

/* Prompt demo — dark card */
.doc-content .prompt-demo {
  background: var(--bg-dark);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-md);
  padding: 18px 20px;
  margin: 18px 0;
}

.doc-content .prompt-demo .pd-label {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: #d4956a;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 10px;
}

.doc-content .prompt-demo p {
  font-size: 0.88rem;
  color: var(--code-text);
  line-height: 1.7;
  margin: 0;
}

.doc-content .prompt-demo .pd-part {
  color: #f0eadf;
  font-weight: 500;
}

.doc-content .u-tabs,
.doc-content .tab-container {
  margin: 1rem 0 1.2rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  overflow: hidden;
  background: var(--bg-page-soft);
}

.doc-content .u-tabs-bar,
.doc-content .tab-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding: 10px;
  border-bottom: 1px solid var(--line);
  background: rgba(168, 91, 47, 0.04);
}

.doc-content .u-tabs-btn,
.doc-content .tab-btn {
  appearance: none;
  border: 1px solid rgba(168, 91, 47, 0.12);
  background: rgba(250, 249, 246, 0.9);
  color: var(--text-soft);
  padding: 6px 10px;
  border-radius: 999px;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  cursor: pointer;
  transition: color var(--transition-fast),
              background var(--transition-fast),
              border-color var(--transition-fast);
}

.doc-content .u-tabs-btn:hover,
.doc-content .tab-btn:hover {
  color: var(--accent-dark);
  background: rgba(168, 91, 47, 0.06);
}

.doc-content .u-tabs-btn.active,
.doc-content .tab-btn.active {
  color: var(--accent-dark);
  background: rgba(168, 91, 47, 0.1);
  border-color: rgba(168, 91, 47, 0.24);
}

.doc-content .u-tabs-panel,
.doc-content .tab-panel {
  display: none;
  padding: 0 16px 16px;
}

.doc-content .u-tabs-panel.active,
.doc-content .tab-panel.active {
  display: block;
}

.doc-content .strategy-num,
.doc-content .pa-num,
.doc-content .callout-icon,
.doc-content .arch-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  border-radius: 999px;
  background: rgba(168, 91, 47, 0.08);
  color: var(--accent-dark);
  border: 1px solid rgba(168, 91, 47, 0.13);
  font-family: var(--font-mono);
  font-size: 0.74rem;
}

.doc-content .example-block,
.doc-content .code-wrap,
.doc-content .table-wrap {
  margin: 1rem 0 1.2rem;
  position: relative;
  overflow-x: auto;
}

.doc-content .u-quiz,
.doc-content .quiz-block {
  margin: 1rem 0 1.2rem;
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 18px;
}

.doc-content .u-option,
.doc-content .quiz-option {
  margin: 8px 0;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: rgba(250, 249, 246, 0.78);
  cursor: pointer;
  transition: border-color var(--transition-fast), background var(--transition-fast);
}

.doc-content .u-option:hover,
.doc-content .quiz-option:hover {
  border-color: var(--line-strong);
  background: var(--bg-page);
}

.doc-content .u-disclosure,
.doc-content .quiz-answer {
  margin-top: 12px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: rgba(250, 249, 246, 0.84);
}

.doc-content .u-disclosure summary,
.doc-content .quiz-answer summary {
  list-style: none;
  cursor: pointer;
  padding: 10px 12px;
  color: var(--accent-dark);
  font-weight: 600;
}

.doc-content .u-disclosure[open] summary,
.doc-content .quiz-answer[open] summary {
  border-bottom: 1px solid var(--line);
}

.doc-content .example-label {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-soft);
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  border-bottom: none;
  padding: 8px 14px;
  border-radius: var(--radius-md) var(--radius-md) 0 0;
}

/* ── Lesson card inner elements ────────────── */
.doc-content .lesson-title {
  font-family: var(--font-display);
  font-size: 1.06rem;
  font-weight: 600;
  color: var(--text-strong);
  margin-bottom: 8px;
}

.doc-content .lesson-num {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--accent);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  white-space: nowrap;
}

.doc-content .lesson-desc {
  font-size: 0.88rem;
  color: var(--text-body);
  line-height: 1.7;
  margin-bottom: 0;
}

.doc-content .tip-list {
  margin: 10px 0 0;
  padding-left: 18px;
}

.doc-content .tip-list li {
  font-size: 0.86rem;
  color: var(--text-body);
  line-height: 1.6;
  margin-bottom: 4px;
}

/* ── Mode grid (Chat / Cowork / Code) ──────── */
.doc-content .mode-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
  margin: 20px 0;
}

.doc-content .mode-card {
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 18px;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.doc-content .mode-card:hover {
  border-color: var(--line-strong);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
}

.doc-content .mode-name {
  font-family: var(--font-display);
  font-size: 0.96rem;
  font-weight: 600;
  color: var(--text-strong);
  margin-bottom: 6px;
}

.doc-content .mode-badge {
  display: inline-block;
  font-size: 0.68rem;
  font-family: var(--font-mono);
  color: var(--accent);
  background: rgba(168, 91, 47, 0.08);
  padding: 2px 7px;
  border-radius: 4px;
  margin-bottom: 10px;
}

.doc-content .mode-desc {
  font-size: 0.86rem;
  color: var(--text-body);
  line-height: 1.6;
}

/* ── Compare grid (2-column side-by-side) ──── */
.doc-content .compare-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin: 18px 0;
}

.doc-content .compare-block {
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 16px 18px;
  transition: border-color var(--transition-fast);
}

.doc-content .compare-block:hover {
  border-color: var(--line-strong);
}

.doc-content .compare-block h4 {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--accent);
  letter-spacing: 0.05em;
  margin-bottom: 10px;
}

.doc-content .compare-block ul {
  padding-left: 16px;
  margin: 0;
}

.doc-content .compare-block li {
  font-size: 0.86rem;
  color: var(--text-body);
  line-height: 1.6;
  margin-bottom: 4px;
}

/* ── Roles grid ────────────────────────────── */
.doc-content .roles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 12px;
  margin: 18px 0;
}

.doc-content .role-card {
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 14px 16px;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.doc-content .role-card:hover {
  border-color: var(--line-strong);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
}

.doc-content .role-name {
  font-size: 0.86rem;
  font-weight: 600;
  color: var(--text-strong);
  margin-bottom: 6px;
}

.doc-content .role-uses {
  font-size: 0.8rem;
  color: var(--text-body);
  line-height: 1.55;
}

/* ── 4D framework grid ─────────────────────── */
.doc-content .d4-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
  margin: 20px 0;
}

.doc-content .d4-cell {
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 18px;
  text-align: center;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.doc-content .d4-cell:hover {
  border-color: var(--line-strong);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
}

.doc-content .d4-label {
  font-family: var(--font-display);
  font-size: 0.96rem;
  font-weight: 600;
  color: var(--text-strong);
  margin-bottom: 10px;
  line-height: 1.4;
}

.doc-content .d4-label small {
  display: block;
  font-size: 0.78rem;
  font-family: var(--font-mono);
  color: var(--accent);
  font-weight: 400;
  margin-top: 4px;
}

.doc-content .d4-desc {
  font-size: 0.82rem;
  color: var(--text-body);
  line-height: 1.6;
}

/* ── Concept grid cells ────────────────────── */
.doc-content .concept-cell {
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 16px 18px;
  transition: border-color var(--transition-fast);
}

.doc-content .concept-cell:hover {
  border-color: var(--line-strong);
}

.doc-content .concept-term {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--accent);
  margin-bottom: 6px;
  letter-spacing: 0.04em;
}

.doc-content .concept-def {
  font-size: 0.86rem;
  color: var(--text-body);
  line-height: 1.6;
}

/* ── Callout variants ──────────────────────── */
.doc-content .callout {
  display: flex;
  gap: 12px;
  padding: 14px 18px;
  border-radius: var(--radius-md);
  margin: 18px 0;
  font-size: 0.88rem;
  line-height: 1.65;
}

.doc-content .callout div {
  color: var(--text-body);
}

.doc-content .callout-tip,
.doc-content .callout.tip {
  background: rgba(168, 91, 47, 0.06);
  border-left: 3px solid var(--accent);
}

.doc-content .callout-note,
.doc-content .callout.note {
  background: rgba(91, 118, 147, 0.07);
  border-left: 3px solid var(--accent-blue);
}

.doc-content .callout-warn,
.doc-content .callout.warning {
  background: rgba(196, 122, 58, 0.07);
  border-left: 3px solid var(--accent-warm);
}

/* ── Rule box ──────────────────────────────── */
.doc-content .rule-box {
  border-left: 4px solid var(--accent);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
}

.doc-content .rule-label {
  font-family: var(--font-mono);
  font-size: 0.66rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--accent);
  margin-bottom: 8px;
}

.doc-content .rule-box p,
.doc-content .rule-box ul {
  margin: 0;
}

.doc-content .rule-box li {
  margin-bottom: 4px;
}

/* ── Warn / Tip boxes ──────────────────────── */
.doc-content .warn-box {
  background: rgba(196, 122, 58, 0.06);
  border-left: 4px solid var(--accent-warm);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  padding: 16px 20px;
  margin: 18px 0;
  font-size: 0.88rem;
  color: var(--text-body);
}

.doc-content .warn-label {
  font-family: var(--font-mono);
  font-size: 0.66rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: #b04a32;
  margin-bottom: 8px;
  font-weight: 600;
}

.doc-content .tip-box {
  background: rgba(107, 130, 88, 0.06);
  border-left: 4px solid var(--accent-olive);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  padding: 16px 20px;
  margin: 18px 0;
  font-size: 0.88rem;
  color: var(--text-body);
}

.doc-content .tip-label {
  font-family: var(--font-mono);
  font-size: 0.66rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: #4a6b3a;
  margin-bottom: 8px;
  font-weight: 600;
}

/* ── Steps ─────────────────────────────────── */
.doc-content .steps {
  margin: 20px 0;
}

.doc-content .step-item {
  display: flex;
  gap: 16px;
  align-items: flex-start;
  padding: 12px 0;
  border-bottom: 1px solid var(--line);
}

.doc-content .step-item:last-child {
  border-bottom: none;
}

.doc-content .step-num {
  width: 32px;
  height: 32px;
  min-width: 32px;
  background: var(--accent);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 0.84rem;
  font-weight: 500;
}

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

.doc-content .step-content p {
  font-size: 0.86rem;
  color: var(--text-body);
  margin: 4px 0 0;
}

/* ── Exercise label ────────────────────────── */
.doc-content .exercise-label {
  font-family: var(--font-mono);
  font-size: 0.66rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--accent);
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  display: inline-block;
  padding: 3px 8px;
  border-radius: 4px;
  margin-bottom: 10px;
}

/* ── Section divider ───────────────────────── */
.doc-content .section-div {
  border: none;
  border-top: 1px solid var(--line);
  margin: 28px 0;
}

/* ── Chapter header (inside doc-content) ───── */
.doc-content .chapter-header {
  margin-bottom: 32px;
  padding-bottom: 24px;
  border-bottom: 2px solid var(--line);
}

.doc-content .chapter-tag {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  display: block;
  margin-bottom: 8px;
}

.doc-content .chapter-intro {
  font-size: 0.9rem;
  color: var(--text-body);
  font-style: italic;
  margin-top: 6px;
}

/* ── Command grid (claude-code-101) ──────────── */
.doc-content .cmd-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 12px;
  margin: 16px 0 24px;
}

.doc-content .cmd-card {
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 14px 16px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.doc-content .cmd-code {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--accent-dark);
  background: rgba(168, 91, 47, 0.07);
  border: 1px solid rgba(168, 91, 47, 0.12);
  border-radius: var(--radius-sm);
  padding: 2px 8px;
  align-self: flex-start;
}

.doc-content .cmd-desc {
  font-size: 0.82rem;
  color: var(--text-body);
  line-height: 1.55;
}

/* ── Use-case grid (mcp-intro) ───────────────── */
.doc-content .uc-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 16px;
  margin: 16px 0 24px;
}

.doc-content .uc-card {
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 18px;
}

.doc-content .uc-header {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 10px;
}

.doc-content .uc-icon {
  font-size: 1.2rem;
}

.doc-content .uc-title {
  font-family: var(--font-display);
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-strong);
}

.doc-content .uc-list {
  margin: 0;
  padding-left: 20px;
  font-size: 0.82rem;
  color: var(--text-body);
  line-height: 1.7;
}

.doc-content .uc-list li {
  margin-bottom: 2px;
}

/* ── Language label (prompt-evaluations) ──────── */
.doc-content .lang-label {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--text-soft);
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  border-bottom: none;
  border-radius: var(--radius-sm) var(--radius-sm) 0 0;
  padding: 3px 10px;
  margin-bottom: -1px;
  position: relative;
  z-index: 1;
}

/* ── Workflow flow (claude-code-101) ──────────── */
.doc-content .workflow-flow {
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
  margin: 16px 0;
  padding: 16px 20px;
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
}

.doc-content .wf-step {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--accent-dark);
  background: var(--bg-page);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 6px 12px;
}

.doc-content .wf-arrow {
  color: var(--text-soft);
  font-size: 1rem;
}

/* ── Flow row/box (mcp-advanced, prompt-engineering) */
.doc-content .flow-row {
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
  margin: 12px 0;
}

.doc-content .flow-box {
  font-size: 0.82rem;
  color: var(--text-body);
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 8px 14px;
}

.doc-content .flow-box.flow-highlight {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent-dark);
  font-weight: 600;
}

.doc-content .flow-arrow {
  color: var(--text-soft);
  font-size: 0.9rem;
  flex-shrink: 0;
}

.doc-content .flow-steps {
  display: flex;
  flex-direction: column;
  gap: 4px;
  margin: 16px 0;
}

.doc-content .flow-step {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  padding: 10px 14px;
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
}

.doc-content .flow-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--accent);
  flex-shrink: 0;
  min-width: 22px;
  width: 22px;
  height: 22px;
  background: rgba(168, 91, 47, 0.1);
  border-radius: 50%;
}

/* ── Architecture stack (claude-code-101, mcp-intro) */
.doc-content .arch-stack {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin: 16px 0;
}

.doc-content .arch-row {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  padding: 12px 16px;
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
}

.doc-content .arch-icon {
  font-size: 1.2rem;
  flex-shrink: 0;
}

.doc-content .arch-role {
  font-weight: 600;
  color: var(--text-strong);
  font-size: 0.88rem;
  min-width: 80px;
  flex-shrink: 0;
}

.doc-content .arch-desc {
  font-size: 0.82rem;
  color: var(--text-body);
  line-height: 1.55;
}

/* ── Highlight box (claude-code-101) ─────────── */
.doc-content .hl-box {
  background: rgba(168, 91, 47, 0.06);
  border: 1px solid rgba(168, 91, 47, 0.15);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius-sm);
  padding: 14px 18px;
  margin: 16px 0;
  font-size: 0.88rem;
  color: var(--text-body);
}

/* ── Step rows (claude-code-101, mcp) ────────── */
.doc-content .step-row {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  padding: 10px 0;
  border-bottom: 1px solid var(--line);
}

.doc-content .step-row:last-child {
  border-bottom: none;
}

.doc-content .step-body {
  font-size: 0.88rem;
  color: var(--text-body);
  line-height: 1.55;
}

.doc-content .step-desc {
  color: var(--text-body);
}

/* ── Grader cards (prompt-evaluations) ───────── */
.doc-content .grader-cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 14px;
  margin: 16px 0;
}

.doc-content .grader-card {
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 18px;
  text-align: center;
}

.doc-content .gc-icon {
  font-size: 1.6rem;
  margin-bottom: 6px;
}

.doc-content .gc-name {
  font-weight: 600;
  font-size: 0.9rem;
  color: var(--text-strong);
  margin-bottom: 8px;
}

.doc-content .grader-card p {
  font-size: 0.8rem;
  color: var(--text-body);
  line-height: 1.5;
  text-align: left;
}

/* ── Score bars (prompt-evaluations) ─────────── */
.doc-content .score-section {
  margin: 16px 0;
}

.doc-content .score-row {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 8px 0;
}

.doc-content .score-label {
  font-size: 0.82rem;
  color: var(--text-body);
  min-width: 200px;
  flex-shrink: 0;
}

.doc-content .score-bar-wrap {
  flex: 1;
  height: 10px;
  background: var(--line);
  border-radius: 5px;
  overflow: hidden;
}

.doc-content .score-bar {
  height: 100%;
  border-radius: 5px;
  transition: width 0.4s ease;
}

.doc-content .score-bar.poor   { background: #c2634a; }
.doc-content .score-bar.medium { background: #d4956a; }
.doc-content .score-bar.good   { background: var(--accent-olive); }

.doc-content .score-value {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-strong);
  min-width: 40px;
  text-align: right;
}

.doc-content .score-note {
  font-size: 0.8rem;
  color: var(--text-soft);
  font-style: italic;
  margin-top: 4px;
}

/* ── Lifecycle (real-world-prompting) ────────── */
.doc-content .lifecycle-block {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin: 16px 0;
}

.doc-content .lifecycle-step {
  display: flex;
  gap: 14px;
  align-items: flex-start;
  padding: 14px 16px;
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
}

.doc-content .step-content {
  font-size: 0.88rem;
  color: var(--text-body);
  line-height: 1.55;
  padding-top: 6px;
}

/* ── Subsection heading ──────────────────────── */
.doc-content .subsection-h3 {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-strong);
  margin: 28px 0 12px;
}

/* ── Exercise titles (prompt-engineering) ─────── */
.doc-content .ex-title,
.doc-content .exercise-title {
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 600;
  color: var(--accent-dark);
  margin: 20px 0 8px;
}

.doc-content .ex-desc {
  font-size: 0.86rem;
  color: var(--text-body);
  margin-bottom: 12px;
}

/* ── Prompt anatomy (prompt-engineering) ──────── */
.doc-content .prompt-anatomy {
  background: var(--bg-page-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 18px;
  margin: 16px 0;
}

.doc-content .pa-title {
  font-weight: 600;
  color: var(--text-strong);
  font-size: 0.9rem;
  margin-bottom: 8px;
}

.doc-content .pa-content {
  font-size: 0.86rem;
  color: var(--text-body);
  line-height: 1.6;
}

/* ── Strategy title ──────────────────────────── */
.doc-content .strategy-title {
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 600;
  color: var(--accent-dark);
  margin: 20px 0 8px;
  padding-bottom: 6px;
  border-bottom: 1px solid var(--line);
}

/* ── Callout variants ────────────────────────── */
.doc-content .callout-title {
  font-weight: 600;
  color: var(--text-strong);
  font-size: 0.9rem;
  margin-bottom: 4px;
}

.doc-content .callout-code {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  background: var(--bg-page-soft);
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  margin-top: 8px;
}

/* ── Warning indicator ───────────────────────── */
.doc-content > .warning,
.doc-content .warning:not(.callout) {
  color: #b04a32;
  font-weight: 600;
}

.doc-content .callout.warning p,
.doc-content .callout.warning li,
.doc-content .callout.warning div {
  color: var(--text-body);
  font-weight: 400;
}

/* ── Lesson body ─────────────────────────────── */
.doc-content .lesson-body {
  font-size: 0.88rem;
  color: var(--text-body);
  line-height: 1.65;
}

/* ── Footer bar (mcp-intro, prompt-evaluations) ── */
.doc-content .footer-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 0;
  margin-top: 20px;
  border-top: 1px solid var(--line);
  font-size: 0.8rem;
  color: var(--text-soft);
}

.doc-content .footer-left,
.doc-content .footer-right {
  font-size: 0.8rem;
  color: var(--text-soft);
}

/* ── In-page TOC (mcp-intro) ────────────────── */
.doc-content .toc-title {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-strong);
  margin-bottom: 10px;
}

.doc-content .toc-item {
  display: block;
  font-size: 0.88rem;
  color: var(--accent);
  text-decoration: none;
  padding: 5px 0;
  border-bottom: 1px solid var(--line);
  transition: color var(--transition-fast);
}

.doc-content .toc-item:hover {
  color: var(--accent-dark);
}

.doc-content .toc-external {
  color: var(--text-soft);
  font-style: italic;
}

/* ── Step list (prompt-evaluations) ──────────── */
.doc-content .step-list {
  counter-reset: step-counter;
  list-style: none;
  padding-left: 0;
  margin: 12px 0;
}

.doc-content .step-list li {
  counter-increment: step-counter;
  padding: 10px 0 10px 36px;
  position: relative;
  border-bottom: 1px solid var(--line);
  font-size: 0.88rem;
  color: var(--text-body);
  line-height: 1.55;
}

.doc-content .step-list li:last-child {
  border-bottom: none;
}

.doc-content .step-list li::before {
  content: counter(step-counter);
  position: absolute;
  left: 0;
  top: 10px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--accent);
  width: 22px;
  height: 22px;
  line-height: 22px;
  text-align: center;
  background: rgba(168, 91, 47, 0.1);
  border-radius: 50%;
}

.doc-content pre,
.doc-content .code-wrap pre {
  overflow-x: auto;
  background: var(--code-bg);
  border-radius: var(--radius-md);
  border: 1px solid #2a261f;
  padding: 18px 18px 20px;
}

/* Flatten top corners when preceded by example-label */
.doc-content .example-label + pre,
.doc-content .example-label + .code-wrap pre {
  border-radius: 0 0 var(--radius-md) var(--radius-md);
}

.doc-content code,
.doc-content pre code {
  font-family: var(--font-mono);
}

.doc-content pre code {
  font-size: 0.82rem;
  line-height: 1.75;
  color: var(--code-text);
}

.doc-content :not(pre) > code {
  background: rgba(168, 91, 47, 0.07);
  border: 1px solid rgba(168, 91, 47, 0.12);
  border-radius: var(--radius-sm);
  padding: 2px 6px;
  color: var(--accent-dark);
  font-size: 0.82em;
}

.copy-btn {
  position: absolute;
  top: 10px;
  right: 12px;
  z-index: 2;
  background: rgba(168, 91, 47, 0.16);
  border: 1px solid rgba(168, 91, 47, 0.26);
  color: var(--code-text);
  font-family: var(--font-mono);
  font-size: 0.68rem;
  border-radius: var(--radius-sm);
  padding: 5px 10px;
  cursor: pointer;
  transition: background var(--transition-fast);
}

.copy-btn:hover {
  background: rgba(168, 91, 47, 0.28);
}

.doc-content table,
.doc-content .ctable {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0 1.4rem;
  font-size: 0.9rem;
}

.doc-content th,
.doc-content td {
  border: 1px solid var(--line);
  padding: 10px 14px;
  vertical-align: top;
  text-align: left;
  line-height: 1.65;
}

.doc-content th {
  background: var(--bg-page-soft);
  color: var(--text-strong);
  font-weight: 600;
  font-size: 0.82rem;
  letter-spacing: 0.01em;
}

.doc-content blockquote {
  margin: 1.2rem 0;
  padding: 16px 20px;
  border-left: 3px solid var(--accent);
  background: rgba(168, 91, 47, 0.04);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  color: var(--text-body);
}

.doc-content .book {
  display: grid;
  gap: 24px;
}

.doc-content .page {
  width: auto;
  min-height: 0;
  margin: 0;
  padding: clamp(22px, 3vw, 34px);
  background: rgba(250, 249, 246, 0.96);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  box-shadow: none;
}

.doc-content .page-num {
  position: static;
  display: block;
  margin-top: 18px;
  text-align: right;
  color: var(--text-soft);
  font-family: var(--font-mono);
}

.doc-content .two-col {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 24px;
}

/* ── Code block (.cb) + comment (.cmt) + subheading (.sub) ── */
.doc-content .cb {
  background: var(--code-bg);
  color: var(--code-text);
  font-family: var(--font-mono);
  font-size: 0.82rem;
  line-height: 1.7;
  padding: 20px 24px;
  border-radius: var(--radius-md);
  white-space: pre-wrap;
  word-break: break-word;
  margin: 12px 0 16px;
  overflow-x: auto;
}

.doc-content .cb .cmt {
  color: #7a8b6e;
  font-style: italic;
}

.doc-content .sub {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-strong);
  margin: 20px 0 8px;
  font-family: var(--font-body);
}

/* ── Sub-section headings (.sh) — skills-guide ── */
.doc-content h2.sh {
  font-family: var(--font-display);
  font-size: 1.15rem !important;
  font-weight: 700;
  color: var(--text-strong);
  margin: 28px 0 10px;
  padding-bottom: 6px;
  border-bottom: 1px solid var(--line);
}

/* ── Checklist (.chk / .chkb) — skills-guide ── */
.doc-content ul.chk {
  list-style: none;
  padding-left: 0;
  margin: 10px 0;
}
.doc-content ul.chk li {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  padding: 4px 0;
  line-height: 1.6;
}
.doc-content .chkb {
  display: inline-block;
  width: 16px;
  height: 16px;
  min-width: 16px;
  border: 2px solid var(--accent);
  border-radius: 3px;
  margin-top: 3px;
  background: var(--bg-page);
}

/* ── Code block (.code-block) — pre-based, mcp-advanced etc. ── */
.doc-content .code-block {
  background: var(--code-bg);
  color: var(--code-text);
  font-family: var(--font-mono);
  font-size: 0.82rem;
  line-height: 1.7;
  padding: 20px 24px;
  border-radius: var(--radius-md);
  margin: 12px 0 16px;
  overflow-x: auto;
  white-space: pre-wrap;
  word-break: break-word;
}
.doc-content .code-block code {
  background: none;
  padding: 0;
  font-size: inherit;
  color: inherit;
}

/* ── Syntax highlighting tokens ── */
.doc-content .code-block .cm,
.doc-content .cb .cm,
.doc-content .cmt {
  color: #7a8b6e;
  font-style: italic;
}
.doc-content .code-block .str,
.doc-content .cb .str {
  color: #c9a56a;
}
.doc-content .code-block .kw,
.doc-content .cb .kw {
  color: #d4879c;
  font-weight: 600;
}
.doc-content .code-block .fn,
.doc-content .cb .fn {
  color: #7eb8d4;
}
.doc-content .code-block .type,
.doc-content .cb .type {
  color: #8cc8a0;
}
.doc-content .code-block .num,
.doc-content .cb .num {
  color: #d4a96a;
}
.doc-content .code-block .dv,
.doc-content .cb .dv {
  color: #d4a96a;
}

/* ── Language labels on code blocks ── */
.doc-content [class^="lang-"],
.doc-content [class^="language-"] {
  /* no extra styling needed — inherits from parent .code-block / .cb */
}

/* ── Good/Bad markers (.gd / .bd) — skills-guide ── */
.doc-content .gd {
  color: #4a6b3a;
  font-weight: 600;
}
.doc-content .bd {
  color: #b04a32;
  font-weight: 600;
}

/* ── Page sub-label (.ptl) — skills-guide ── */
.doc-content .ptl {
  font-family: var(--font-display);
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin: 24px 0 8px;
}

/* ── Chapter nav prev link ── */
.chapter-nav__link--prev {
  text-align: left;
}

/* ── Attribution footer (non-book variant) ── */
.attribution {
  text-align: center;
  font-size: 0.82rem;
  color: var(--text-soft);
  padding: 16px 0;
  border-top: 1px solid var(--line);
  margin-top: var(--space-xl);
}
.attribution a {
  color: var(--accent-dark);
  text-decoration: none;
}
.attribution a:hover {
  text-decoration: underline;
}

/* ── MCP-intro page layout (.container / .layout / .toc / .main-content) ── */
.doc-content > .container {
  display: block;
}
.doc-content .layout {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 32px;
  align-items: start;
}
.doc-content .layout > .toc {
  position: sticky;
  top: 24px;
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 12px 0;
  border-right: 1px solid var(--line);
}
.doc-content .toc .toc-title {
  font-family: var(--font-display);
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-soft);
  margin-bottom: 8px;
}
.doc-content .toc .toc-item {
  display: flex;
  font-size: 0.82rem;
  color: var(--text-body);
  text-decoration: none;
  padding: 4px 12px 4px 0;
  border-bottom: none;
  border-radius: var(--radius-sm);
  transition: color var(--transition-fast);
}
.doc-content .toc .toc-item:hover {
  color: var(--accent);
}
.doc-content .toc .toc-item:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}
.doc-content .toc .toc-external {
  margin-top: 8px;
  color: var(--accent-dark);
  font-weight: 600;
  font-style: normal;
}
.doc-content .main-content {
  min-width: 0;
}

.book-footer {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  flex-wrap: wrap;
  margin: 4px auto 0;
  padding: 0 10px;
  color: var(--text-soft);
  font-size: 0.78rem;
  line-height: 1.8;
}

.book-footer a {
  color: var(--accent-dark);
  text-decoration: none;
}

@media (max-width: 980px) {
  .book-topline {
    flex-direction: column;
    align-items: flex-start;
  }

  .book-topline__nav {
    justify-content: flex-start;
  }

  .page {
    padding: 28px 24px 56px;
    min-height: 0;
  }

  .page-num {
    right: 24px;
  }

  .page-cover__inner {
    padding: 42px 28px 56px;
    min-height: 0;
  }

  .page-cover {
    min-height: 0;
  }
}

@media (max-width: 760px) {
  body.page-doc-book {
    padding: 22px 10px 48px;
  }

  .doc-content .two-col,
  .doc-content .pa-item,
  .doc-content .arch-row,
  .meta-grid {
    grid-template-columns: 1fr;
  }

  .doc-content .strategy-grid,
  .doc-content .concept-grid,
  .doc-content .eval-component-grid,
  .doc-content .mode-grid {
    grid-template-columns: 1fr;
  }

  .doc-content .d4-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .page-title {
    font-size: 2.3rem;
  }

  .doc-content .layout {
    grid-template-columns: 1fr;
  }
  .doc-content .layout > .toc {
    position: static;
    border-right: none;
    border-bottom: 1px solid var(--line);
    flex-direction: row;
    flex-wrap: wrap;
    gap: 4px 12px;
    padding-bottom: 12px;
    margin-bottom: 12px;
  }
}

@media (max-width: 640px) {
  body.page-doc-book {
    padding: 14px 6px 40px;
  }

  .book-topline {
    padding: 0 6px;
  }

  .book-topline__nav {
    gap: 6px;
  }

  .book-pill-nav {
    padding: 6px 10px;
    font-size: 0.72rem;
  }

  .doc-content .compare-grid,
  .doc-content .d4-grid {
    grid-template-columns: 1fr;
  }

  .doc-content .cmd-grid,
  .doc-content .uc-grid,
  .doc-content .grader-cards {
    grid-template-columns: 1fr;
  }

  .doc-content .score-label {
    min-width: 120px;
    font-size: 0.75rem;
  }

  .doc-content .arch-row {
    flex-direction: column;
    gap: 4px;
  }

  .doc-content .workflow-flow {
    flex-direction: column;
    align-items: stretch;
  }

  .doc-content .wf-arrow {
    text-align: center;
  }

  .doc-content .flow-row {
    flex-direction: column;
    align-items: stretch;
  }

  .doc-content .flow-arrow {
    text-align: center;
  }

  .doc-content .cb {
    padding: 14px 16px;
    font-size: 0.78rem;
  }

  .page {
    padding: 20px 16px 48px;
    border-radius: var(--radius-md);
  }

  .page-num {
    right: 16px;
    bottom: 20px;
  }

  .page-cover__inner {
    padding: 28px 16px 40px;
  }

  .page-cover {
    min-height: 0;
  }

  .page-cover__footer {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }

  .page-cover__meta {
    text-align: left;
  }

  .page-cover__title {
    font-size: clamp(2.2rem, 8vw, 3.8rem);
    line-height: 1.04;
  }

  .page-title {
    font-size: 1.8rem;
  }

  .chapter-page__title {
    font-size: 1.6rem;
  }

  .doc-content .u-grid {
    grid-template-columns: 1fr;
  }

  .doc-content .code-block {
    padding: 14px 16px;
    font-size: 0.78rem;
  }
}

/* Chapter navigation */
.chapter-nav {
  display: flex;
  justify-content: space-between;
  gap: var(--space-md);
  margin-top: var(--space-2xl);
  padding-top: var(--space-lg);
  border-top: 1px solid var(--line);
}

.chapter-nav__link {
  display: flex;
  flex-direction: column;
  gap: 4px;
  text-decoration: none;
  padding: 12px 16px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--bg-page);
  max-width: 48%;
  transition: border-color var(--transition-fast),
              box-shadow var(--transition-fast),
              transform var(--transition-fast);
}

.chapter-nav__link:hover {
  border-color: var(--accent);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
  transform: translateY(-1px);
}

.chapter-nav__link--next {
  margin-left: auto;
  text-align: right;
}

.chapter-nav__dir {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
}

.chapter-nav__title {
  font-size: 0.88rem;
  color: var(--text-strong);
  font-weight: 500;
  line-height: 1.4;
}

/* Attribution block */
.book-attribution {
  margin: var(--space-lg) auto 0;
  padding: var(--space-md) var(--space-lg);
  max-width: 1100px;
  text-align: center;
  font-size: 0.78rem;
  color: var(--text-soft);
  line-height: 1.8;
}

.book-attribution a {
  color: var(--accent-dark);
  text-decoration: none;
}

.book-attribution a:hover {
  text-decoration: underline;
}

/* Back-to-top button */
.back-to-top {
  position: fixed;
  bottom: 32px;
  right: 32px;
  z-index: 100;
  width: 40px;
  height: 40px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--bg-page);
  color: var(--text-soft);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-page);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-normal),
              transform var(--transition-normal),
              border-color var(--transition-fast);
}

.back-to-top.is-visible {
  opacity: 1;
  pointer-events: auto;
}

.back-to-top:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
}

.back-to-top svg {
  width: 18px;
  height: 18px;
}

/* Reading progress bar */
.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 0%;
  height: 2px;
  background: var(--accent);
  z-index: 200;
  transition: width 0.1s linear;
}

/* Link underline animation */
.doc-content a {
  color: var(--accent-dark);
  text-decoration: underline;
  text-decoration-color: rgba(168, 91, 47, 0.25);
  text-underline-offset: 2px;
  transition: text-decoration-color var(--transition-fast);
}

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

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }

  .reading-progress {
    transition: none;
  }
}

/* Print styles */
@media print {
  .book-topline,
  .back-to-top,
  .reading-progress,
  .chapter-nav,
  .book-footer,
  .book-attribution,
  .copy-btn,
  .tab-bar,
  .book-pill-nav {
    display: none !important;
  }

  .doc-content .u-tabs-panel,
  .doc-content .tab-panel {
    display: block !important;
  }

  .page {
    box-shadow: none;
    border: 1px solid #ccc;
    break-inside: avoid;
  }

  /* Print: scrim hidden, revert cover text to dark for white-paper readability */
  .page-cover::before { display: none; }
  .page-cover__eyebrow { color: #2c2b25; }
  .page-cover__title { color: #1a1915; }
  .page-cover__summary { color: #2c2b25; }
  .page-cover__brand .site-brand__mark { color: #1a1915; }
  .page-cover__brand-name { color: #1a1915; }
  .page-cover__brand-sub { color: #4e4a40; }
  .page-cover__meta { color: #4e4a40; }
}