/* Chapter reading experience — real HTML text, not page screenshots */

body.chapter-page {
  background:
    radial-gradient(900px 420px at 0% 0%, rgba(13, 122, 111, 0.08), transparent 55%),
    linear-gradient(180deg, #eef3f0 0%, var(--paper) 35%, #e8efe9 100%);
  min-height: 100vh;
}

.chapter-shell {
  display: grid;
  grid-template-columns: var(--sidebar-w) 1fr;
  min-height: 100vh;
}

.chapter-page .sidebar {
  background: rgba(243, 246, 244, 0.96);
  border-right: 1px solid var(--line);
  position: sticky;
  top: 0;
  height: 100vh;
  overflow: auto;
  padding: 1rem 0.65rem 2rem;
}

.chapter-page .sidebar .brand {
  display: inline-flex;
  margin: 0.35rem 0.5rem 1rem;
}

.chapter-main {
  min-width: 0;
}

.chapter-toolbar {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.85rem 1.25rem;
  border-bottom: 1px solid var(--line);
  background: rgba(243, 246, 244, 0.88);
  backdrop-filter: blur(10px);
  position: sticky;
  top: 0;
  z-index: 20;
}

.toolbar-spacer {
  flex: 1;
}

.btn-small {
  padding: 0.45rem 0.9rem;
  font-size: 0.85rem;
}

.chapter-article {
  width: min(760px, calc(100% - 2.5rem));
  margin: 0 auto;
  padding: 2rem 0 4.5rem;
}

.part-eyebrow {
  margin: 0 0 0.75rem;
  font-size: 0.75rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 700;
}

.chapter-hero {
  margin-bottom: 2rem;
  padding-bottom: 1.25rem;
  border-bottom: 1px solid var(--line);
}

.chapter-num {
  margin: 0 0 0.4rem;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent);
}

.chapter-hero h1 {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(2rem, 5vw, 3rem);
  letter-spacing: -0.03em;
  line-height: 1.1;
}

.chapter-body {
  font-size: 1.05rem;
  line-height: 1.7;
  color: var(--ink);
}

.chapter-body > * + * {
  margin-top: 1.15rem;
}

.chapter-body p {
  margin: 0;
  color: var(--ink-soft);
}

.chapter-body h2,
.chapter-body h3 {
  margin: 2rem 0 0;
  font-family: var(--font-display);
  letter-spacing: -0.02em;
  line-height: 1.2;
  color: var(--ink);
}

.chapter-body h2 {
  font-size: 1.45rem;
}

.chapter-body h3 {
  font-size: 1.15rem;
}

.section-label {
  font-family: var(--font-body) !important;
  font-size: 0.78rem !important;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent) !important;
  font-weight: 700;
}

.code-block {
  margin: 1.35rem 0;
  border: 1px solid rgba(15, 28, 36, 0.12);
  background: #0f1c24;
  overflow: hidden;
  box-shadow: var(--shadow);
}

.code-lang {
  padding: 0.45rem 0.85rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  color: #7fb4f0;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}

pre.code {
  margin: 0;
  padding: 1rem 1.1rem 1.15rem;
  overflow-x: auto;
  background: transparent;
}

pre.code code {
  font-family: var(--font-mono);
  font-size: 0.86rem;
  line-height: 1.55;
  color: #e8ecf6;
  white-space: pre;
}

figure.diagram {
  margin: 1.75rem 0;
  background: #fff;
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
  overflow: hidden;
}

figure.diagram.native {
  background: transparent;
  border: 1px solid var(--line);
}

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

figure.diagram figcaption {
  padding: 0.7rem 0.9rem;
  font-size: 0.85rem;
  color: var(--ink-soft);
  border-top: 1px solid var(--line);
}

.table-wrap {
  margin: 1.35rem 0 1.6rem;
  overflow-x: auto;
  border: 1px solid var(--line);
  background: #fff;
  box-shadow: var(--shadow);
}

.table-wrap table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;
}

.table-wrap caption {
  text-align: left;
  padding: 0.75rem 0.9rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.04em;
  color: var(--accent);
  border-bottom: 1px solid var(--line);
}

.table-wrap th,
.table-wrap td {
  padding: 0.7rem 0.85rem;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid rgba(15, 28, 36, 0.08);
  color: var(--ink-soft);
}

.table-wrap th {
  font-size: 0.8rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--ink);
  background: rgba(13, 122, 111, 0.06);
  font-weight: 700;
}

.table-wrap tr:last-child td {
  border-bottom: 0;
}

.table-wrap td:first-child {
  font-weight: 650;
  color: var(--ink);
  white-space: nowrap;
}

.diagram-card img {
  aspect-ratio: 16 / 10;
  object-fit: contain;
  object-position: center;
  background: #f7faf8;
  padding: 0.5rem;
}

.chapter-pager {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--line);
}

.chapter-pager a {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  max-width: 45%;
  padding: 0.85rem 0;
  color: var(--ink-soft);
  transition: color 0.2s ease;
}

.chapter-pager a:hover {
  color: var(--accent-deep);
}

.chapter-pager .dir {
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
}

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

.chapter-page .toc-group-title {
  font-size: 0.7rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
  padding: 0.45rem 0.65rem;
  font-weight: 700;
}

.chapter-page .toc-item {
  display: block;
  padding: 0.42rem 0.65rem;
  border-radius: 8px;
  color: var(--ink-soft);
  font-size: 0.88rem;
}

.chapter-page .toc-item:hover,
.chapter-page .toc-item.active {
  background: var(--accent-glow);
  color: var(--accent-deep);
}

.chapter-page .toc-item .num {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  margin-right: 0.35rem;
  opacity: 0.8;
}

@media (max-width: 900px) {
  .chapter-shell {
    grid-template-columns: 1fr;
  }

  .chapter-page .sidebar {
    position: fixed;
    inset: 0 auto 0 0;
    width: min(86vw, 320px);
    z-index: 80;
    transform: translateX(-105%);
    transition: transform 0.3s var(--ease);
    box-shadow: var(--shadow);
  }

  body.sidebar-open .chapter-page .sidebar,
  body.sidebar-open .sidebar {
    transform: translateX(0);
  }
}