.book-page {
  padding: 48px 0 96px;
}

.book-breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin-bottom: 28px;
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.book-breadcrumb a {
  color: var(--soft-ink);
  text-decoration: none;
}

.book-breadcrumb a:hover,
.book-breadcrumb a:focus-visible {
  color: var(--accent);
}

.book-breadcrumb__sep {
  color: var(--muted);
}

.book-header {
  max-width: var(--prose-width);
  margin-bottom: 56px;
}

.book-subtitle {
  margin: 12px 0 0;
  font-family: var(--mono);
  font-size: 0.85rem;
  letter-spacing: 0.06em;
  color: var(--accent);
}

.book-intro {
  margin: 20px 0 0;
  font-size: 1.05rem;
  line-height: 1.65;
  color: var(--soft-ink);
}

.book-strands {
  display: grid;
  gap: 40px;
}

.book-strand__title {
  margin: 0 0 16px;
  font-size: 1.5rem;
}

.book-chapter-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 10px;
}

.book-chapter-link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 16px 20px;
  border: 1px solid var(--card-border);
  border-radius: 12px;
  background: var(--card-bg);
  text-decoration: none;
  color: var(--ink);
  transition: border-color 200ms ease, box-shadow 200ms ease;
}

a.book-chapter-link:hover,
a.book-chapter-link:focus-visible {
  border-color: var(--accent);
  box-shadow: 0 6px 20px var(--shadow-soft);
}

.book-chapter-link--disabled {
  opacity: 0.72;
  cursor: default;
}

.book-chapter-item--planned .book-chapter-link__title {
  color: var(--soft-ink);
}

.book-chapter-link__title {
  font-family: var(--font-heading);
  font-size: 1.15rem;
}

.book-chapter-badge {
  flex-shrink: 0;
  font-family: var(--mono);
  font-size: 0.65rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding: 4px 10px;
  border-radius: 999px;
}

.book-chapter-badge--live {
  color: var(--accent);
  background: rgba(154, 107, 46, 0.12);
}

.book-chapter-badge--planned {
  color: var(--muted);
  background: rgba(118, 118, 118, 0.12);
}

.book-chapter {
  max-width: var(--prose-width);
}

.book-chapter__header {
  margin-bottom: 32px;
}

.book-chapter__lead {
  margin: 16px 0 0;
  font-size: 1.05rem;
  line-height: 1.65;
  color: var(--soft-ink);
}

.book-prose {
  font-size: 1rem;
  line-height: 1.7;
  color: var(--ink);
}

.book-prose > p {
  margin: 0 0 1.1em;
}

.book-prose__heading {
  margin: 2em 0 0.6em;
  font-size: 1.35rem;
}

.book-formula {
  margin: 0;
  font-family: var(--mono);
  font-size: 1.1rem;
  letter-spacing: 0.02em;
}

.book-formula--inline {
  font-size: 0.95rem;
}

.book-callout {
  margin: 1.5em 0;
  padding: 18px 20px;
  border-left: 3px solid var(--accent);
  border-radius: 0 10px 10px 0;
  background: var(--card-bg);
}

.book-callout--formula {
  text-align: center;
  border-left: none;
  border: 1px solid var(--card-border);
  border-radius: 12px;
}

.book-callout--dse {
  border-left-color: var(--muted);
}

.book-callout__label {
  margin: 0 0 8px;
  font-family: var(--mono);
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
}

.book-table-wrap {
  margin: 1.25em 0 1.5em;
  overflow-x: auto;
}

.book-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.92rem;
  border: 1px solid var(--line);
}

.book-table th,
.book-table td {
  padding: 12px 14px;
  text-align: left;
  border: 1px solid var(--line);
  vertical-align: top;
}

.book-table thead th {
  font-family: var(--mono);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink);
  background: rgba(154, 107, 46, 0.08);
}

.book-table tbody td:first-child {
  font-family: var(--mono);
  font-size: 0.88rem;
}

.book-table tbody tr:nth-child(even) td {
  background: rgba(154, 107, 46, 0.04);
}

.book-prose .katex {
  font-size: 1.05em;
}

.book-formula .katex-display {
  margin: 0;
}

.math-widget-mount {
  margin-top: 40px;
  max-width: 960px;
}

.book-page--chapter .book-callout--dse {
  max-width: var(--prose-width);
  margin-top: 2rem;
}

@media (min-width: 900px) {
  .book-page--chapter .book-chapter {
    max-width: none;
  }

  .book-prose {
    max-width: var(--prose-width);
  }
}