/* ================================================================
   Editorial · chapter pages  (Pandoc → HTML)
   Responsive: mobile < 768px | tablet 768–1023px | desktop ≥ 1024px
   ================================================================ */

:root {
  --paper:        #efebe3;
  --ink:          #1c1c1c;
  --ink-muted:    #5c5a54;
  --rule:         rgba(28, 28, 28, 0.18);
  --accent:       #722f37;
  --accent-hover: #4a1f24;
  --toc-width:    18rem;
  --shell-max:    72rem;
  --shell-pad:    1.25rem;
}

/* ── Reset & base ─────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

.chapter-page {
  font-family: "Source Sans 3", system-ui, sans-serif;
  background: var(--paper);
  color: var(--ink);
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  scroll-behavior: smooth;
}

/* ── Shell ────────────────────────────────────────────────── */
.chapter-shell {
  max-width: var(--shell-max);
  margin: 0 auto;
  padding: 1.5rem var(--shell-pad) 3rem;
  border-top: 3px double var(--ink);
}

/* ── Top nav ──────────────────────────────────────────────── */
.chapter-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-bottom: 1.25rem;
  margin-bottom: 1.75rem;
  border-bottom: 1px solid var(--rule);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}
.chapter-nav a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 0.15s, border-color 0.15s;
}
.chapter-nav a:hover {
  color: var(--accent-hover);
  border-bottom-color: var(--accent-hover);
}

/* ── Masthead ─────────────────────────────────────────────── */
.chapter-masthead__kicker {
  font-size: 0.6875rem;
  font-weight: 600;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin-bottom: 0.65rem;
}
.chapter-masthead__title {
  font-family: "Newsreader", Georgia, serif;
  font-size: clamp(1.5rem, 4vw, 2rem);
  font-weight: 600;
  line-height: 1.18;
  letter-spacing: -0.02em;
  margin: 0 0 1.75rem;
  padding-bottom: 1.25rem;
  border-bottom: 1px solid var(--ink);
}

/* ================================================================
   LAYOUT
   Mobile  (< 768px):   single column, TOC above prose as <details>
   Tablet  (768–1023):  single column, TOC above prose as <details>
   Desktop (≥ 1024px):  grid: prose | TOC sticky
   ================================================================ */

/* ── Mobile / Tablet: single column ──────────────────────── */
.chapter-layout {
  display: flex;
  flex-direction: column;
  gap: 0;
}

/* ── TOC panel ── mobile / tablet ─────────────────────────── */
.chapter-toc-panel {
  order: -1;           /* visually above prose */
  font-size: 0.8125rem;
  margin-bottom: 1.75rem;
}
.chapter-toc-panel[hidden] { display: none !important; }

/* <details> wrapper */
.chapter-toc__details {
  border: 1px solid var(--rule);
  border-radius: 5px;
  overflow: hidden;
}

/* <summary> toggle label */
.chapter-toc__summary {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.7rem 1rem;
  font-size: 0.65rem;
  font-weight: 600;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--ink-muted);
  cursor: pointer;
  user-select: none;
  list-style: none;
  background: rgba(28, 28, 28, 0.03);
}
.chapter-toc__summary::-webkit-details-marker { display: none; }
.chapter-toc__summary::after {
  content: "▸";
  margin-left: auto;
  font-size: 0.8rem;
  color: var(--ink);
  transition: transform 0.2s ease;
}
.chapter-toc__details[open] > .chapter-toc__summary::after {
  transform: rotate(90deg);
}

/* nav inside details */
.chapter-toc__details nav {
  padding: 0.75rem 1rem 1rem;
  border-top: 1px solid var(--rule);
}

/* ── TOC tree ─────────────────────────────────────────────── */
.chapter-toc__tree {
  margin: 0;
  padding-left: 1rem;
  list-style: decimal;
}
.chapter-toc__tree .chapter-toc__tree {
  margin-top: 0.3rem;
  margin-bottom: 0.3rem;
  padding-left: 0.9rem;
  list-style: lower-latin;
}
.chapter-toc__tree .chapter-toc__tree .chapter-toc__tree {
  list-style: lower-roman;
}
.chapter-toc__tree li { margin-bottom: 0.3rem; }
.chapter-toc__tree a {
  color: var(--ink);
  text-decoration: none;
  line-height: 1.35;
  border-bottom: 1px solid transparent;
  transition: color 0.15s, border-color 0.15s;
}
.chapter-toc__tree a:hover {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

/* ── Desktop (≥ 1024px): 2-column, TOC sticky on right ────── */
@media (min-width: 1024px) {
  .chapter-shell {
    padding-left: 2rem;
    padding-right: 2rem;
  }

  .chapter-layout {
    display: grid;
    grid-template-columns: minmax(0, 1fr) var(--toc-width);
    grid-template-areas: "prose toc";
    column-gap: 3rem;
    align-items: start;
  }

  .chapter-prose      { grid-area: prose; }
  .chapter-toc-panel  { grid-area: toc; order: 0; margin-bottom: 0; }

  /* Sticky panel */
  .chapter-toc-panel {
    position: sticky;
    top: 1.5rem;
    max-height: calc(100vh - 3rem);
    overflow-y: auto;
    scrollbar-width: thin;
  }

  /* On desktop: remove box, show as borderless sidebar */
  .chapter-toc__details {
    border: none;
    border-radius: 0;
    overflow: visible;
    border-left: 1px solid rgba(28, 28, 28, 0.15);
    padding-left: 1.25rem;
  }

  /* Hide toggle arrow, summary becomes plain label — sticky khi TOC cuộn */
  .chapter-toc__summary {
    position: sticky;
    top: 0;
    z-index: 1;
    background: var(--paper);
    padding: 0.35rem 0 0.65rem;
    cursor: default;
    pointer-events: none;
    border-bottom: 1px solid var(--ink);
    margin-bottom: 0.75rem;
  }
  .chapter-toc__summary::after { display: none; }

  /* Always show nav content on desktop (open forced by JS, CSS fallback) */
  .chapter-toc__details > nav {
    display: block !important;
    padding: 0;
    border-top: none;
  }
}

/* ── Prose content ────────────────────────────────────────── */
.chapter-prose { font-size: 1.02rem; }

.chapter-prose h1,
.chapter-prose h2,
.chapter-prose h3,
.chapter-prose h4 {
  font-family: "Newsreader", Georgia, serif;
  font-weight: 600;
  line-height: 1.25;
  margin: 2rem 0 0.75rem;
  letter-spacing: -0.01em;
  scroll-margin-top: 4rem;
}
.chapter-prose h1 { font-size: 1.35rem; }
.chapter-prose h2 { font-size: 1.2rem; }
.chapter-prose h3 { font-size: 1.08rem; }
.chapter-prose h4 { font-size: 1rem; color: var(--ink-muted); }

.chapter-prose p {
  margin: 0 0 0.9rem;
  text-align: justify;
  hyphens: auto;
}

.chapter-prose ul,
.chapter-prose ol {
  margin: 0 0 1rem;
  padding-left: 1.35rem;
}
.chapter-prose li { margin-bottom: 0.35rem; }

.chapter-prose strong { font-weight: 600; }
.chapter-prose em     { font-style: italic; }

.chapter-prose blockquote {
  margin: 1rem 0;
  padding: 0.5rem 0 0.5rem 1rem;
  border-left: 2px solid var(--accent);
  color: var(--ink-muted);
  font-style: italic;
}

.chapter-prose code {
  font-size: 0.9em;
  background: rgba(28, 28, 28, 0.06);
  padding: 0.1em 0.35em;
  border-radius: 3px;
}
.chapter-prose pre {
  overflow-x: auto;
  font-size: 0.85rem;
  padding: 0.85rem 1rem;
  background: rgba(28, 28, 28, 0.05);
  border-radius: 4px;
  margin: 1rem 0;
}

.chapter-prose table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
  margin: 1.25rem 0;
  display: block;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}
.chapter-prose th,
.chapter-prose td {
  border: 1px solid var(--rule);
  padding: 0.4rem 0.55rem;
  vertical-align: top;
}
.chapter-prose th {
  font-weight: 600;
  background: rgba(28, 28, 28, 0.04);
}

.chapter-prose .math.display {
  margin: 1rem 0;
  overflow-x: auto;
}

/* ── Stub (Pandoc thất bại) ───────────────────────────────── */
.stub-note  { font-style: italic; color: var(--ink-muted); margin-bottom: 1rem; }
.stub-links a { color: var(--accent); font-weight: 600; }

/* ── Prev / Next chapter pager ───────────────────────────── */
.chapter-pager {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 3rem;
  padding-top: 1.75rem;
  border-top: 1px solid var(--ink);
}

.chapter-pager__btn {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  flex: 0 0 calc(50% - 0.5rem);
  padding: 1rem 1.1rem;
  text-decoration: none;
  color: var(--ink);
  background: rgba(255, 255, 255, 0.45);
  border: 1px solid rgba(28, 28, 28, 0.14);
  border-radius: 7px;
  transition: border-color 0.18s ease, background 0.18s ease, transform 0.15s ease;
}
.chapter-pager__btn:hover {
  border-color: var(--accent);
  background: rgba(114, 47, 55, 0.05);
  transform: translateY(-2px);
}
.chapter-pager__btn:hover .chapter-pager__arrow { opacity: 1; }
.chapter-pager__btn--prev:hover .chapter-pager__arrow { transform: translateX(-3px); }
.chapter-pager__btn--next {
  justify-content: flex-end;
  text-align: right;
  flex-direction: row-reverse;
}
.chapter-pager__btn--next:hover .chapter-pager__arrow { transform: translateX(3px); }

.chapter-pager__arrow {
  font-size: 1.4rem;
  line-height: 1;
  color: var(--accent);
  opacity: 0.55;
  flex-shrink: 0;
  transition: opacity 0.18s ease, transform 0.18s ease;
}

.chapter-pager__info {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  min-width: 0;
  overflow: hidden;
}

.chapter-pager__dir {
  font-size: 0.58rem;
  font-weight: 600;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--ink-muted);
}
.chapter-pager__num {
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--accent);
  letter-spacing: 0.04em;
}
.chapter-pager__title {
  font-family: "Newsreader", Georgia, serif;
  font-size: 0.92rem;
  font-weight: 500;
  line-height: 1.3;
  color: var(--ink);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* Nếu chỉ có 1 nút thì không chiếm hết 50% */
.chapter-pager__btn:only-child { flex: 0 0 auto; }

/* Mobile (< 640px): xếp dọc, full-width */
@media (max-width: 639px) {
  .chapter-pager { flex-direction: column; gap: 0.75rem; }
  .chapter-pager__btn,
  .chapter-pager__btn--next {
    flex: unset;
    flex-direction: row;
    justify-content: flex-start;
    text-align: left;
    width: 100%;
  }
  .chapter-pager__title { white-space: normal; }
}

/* ── Footer ───────────────────────────────────────────────── */
.chapter-footer {
  margin-top: 3rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--ink);
  font-size: 0.8rem;
  text-align: center;
}
.chapter-footer a {
  color: var(--ink);
  text-decoration: none;
  border-bottom: 1px solid rgba(28, 28, 28, 0.35);
  transition: border-color 0.15s;
}
.chapter-footer a:hover { border-bottom-color: var(--ink); }
.chapter-footer__sep { margin: 0 0.5rem; color: var(--ink-muted); }

/* ── Small mobile tweak (< 480px) ────────────────────────── */
@media (max-width: 479px) {
  :root { --shell-pad: 1rem; }
  .chapter-masthead__title { font-size: 1.45rem; }
  .chapter-prose { font-size: 0.97rem; }
}