/* Reader layout */
.reader-shell {
  display: grid;
  grid-template-columns: 280px minmax(0, 1fr);
  gap: 0;
  align-items: start;
  max-width: 1160px;
  margin: 0 auto;
  padding: 0 32px 90px;
}

.reader-toc {
  position: sticky;
  top: 78px;
  align-self: start;
  max-height: calc(100vh - 100px);
  overflow-y: auto;
  padding: 34px 26px 34px 0;
  border-right: 1px solid var(--line);
}
.reader-toc-title {
  font-size: 0.78rem;
  letter-spacing: 0.03em;
  color: var(--sage);
  font-style: italic;
  margin: 0 0 16px;
}
.reader-toc-part { margin-bottom: 18px; }
.reader-toc-part h4 {
  font-family: var(--font-body);
  font-style: italic;
  font-weight: 500;
  color: var(--ink-soft);
  font-size: 0.86rem;
  margin: 0 0 6px;
}
.reader-toc ul { list-style: none; margin: 0; padding: 0; }
.reader-toc li { margin: 0; }
.reader-toc button {
  display: block;
  width: 100%;
  text-align: left;
  background: none;
  border: none;
  font-family: var(--font-body);
  font-size: 0.94rem;
  color: var(--ink-soft);
  padding: 6px 10px 6px 0;
  cursor: pointer;
  border-left: 2px solid transparent;
  padding-left: 10px;
  line-height: 1.3;
}
.reader-toc button:hover { color: var(--teal-dark); }
.reader-toc li.active button {
  color: var(--rust);
  border-left-color: var(--rust);
  font-weight: 600;
}

.reader-main { padding: 34px 0 0 56px; min-width: 0; }

.reader-toolbar {
  display: flex;
  align-items: center;
  gap: 18px;
  position: sticky;
  top: 78px;
  background: var(--cream);
  padding: 10px 0 14px;
  z-index: 5;
  border-bottom: 1px solid var(--line-soft);
  margin-bottom: 30px;
}
.reader-icon-btn {
  display: none;
  background: var(--cream-light);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  width: 38px;
  height: 34px;
  cursor: pointer;
  font-size: 1rem;
  color: var(--teal-dark);
  flex-shrink: 0;
}
.reader-progress {
  flex: 1;
  height: 3px;
  background: var(--line);
}
.reader-progress-bar { height: 100%; background: var(--rust); width: 0%; transition: width 0.2s ease; }
.font-controls { display: flex; gap: 6px; flex-shrink: 0; }
.font-controls button {
  width: 34px;
  height: 34px;
  border: 1px solid var(--line);
  background: var(--cream-light);
  color: var(--teal-dark);
  cursor: pointer;
  border-radius: var(--radius);
  font-family: var(--font-body);
  font-size: 0.85rem;
}
.font-controls button:hover { border-color: var(--rust); color: var(--rust); }

.listen-btn {
  display: flex;
  align-items: center;
  gap: 7px;
  flex-shrink: 0;
  border: 1px solid var(--line);
  background: var(--cream-light);
  color: var(--teal-dark);
  cursor: pointer;
  border-radius: var(--radius);
  padding: 0 14px;
  height: 34px;
  font-family: var(--font-body);
  font-size: 0.88rem;
}
.listen-btn:hover { border-color: var(--rust); color: var(--rust); }
.listen-btn.playing { background: var(--rust); border-color: var(--rust); color: #fff; }
.listen-btn[hidden] { display: none; }
.listen-btn:disabled { opacity: 0.4; cursor: default; }
@media (max-width: 640px) {
  .listen-btn-label { display: none; }
  .listen-btn { padding: 0 9px; }
}

.listen-progress-wrap {
  display: flex;
  align-items: center;
  gap: 10px;
  max-width: 660px;
  font-size: 12px;
  color: var(--ink-soft);
  padding: 10px 0 0;
}
.listen-progress-wrap[hidden] { display: none; }
.listen-progress-wrap input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  flex: 1;
  height: 3px;
  border-radius: 2px;
  background: var(--line);
  outline: none;
}
.listen-progress-wrap input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 12px; height: 12px; border-radius: 50%;
  background: var(--rust); cursor: pointer;
}
.listen-progress-wrap input[type="range"]::-moz-range-thumb {
  width: 12px; height: 12px; border-radius: 50%; border: none;
  background: var(--rust); cursor: pointer;
}
.listen-error {
  max-width: 660px;
  min-height: 1em;
  margin: 6px 0 0;
  font-size: 0.85rem;
  color: var(--rust-dark);
}

.reader-content {
  max-width: 660px;
  font-size: var(--reader-font-size, 1.13rem);
  line-height: 1.75;
}
.reader-content .reader-part {
  font-style: italic;
  color: var(--sage);
  font-size: 0.95rem;
  margin: 0 0 8px;
}
.reader-content .reader-part-image {
  max-width: 320px;
  margin: 0 auto 32px;
}
.reader-content .reader-part-image img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 1086 / 1448;
  object-fit: cover;
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
}
@media (max-width: 640px) {
  .reader-content .reader-part-image { max-width: 220px; }
}
.reader-content .reader-chapter-image {
  max-width: 660px;
  margin: 28px 0 36px;
}
.reader-content .reader-chapter-image img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 1448 / 1086;
  object-fit: cover;
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
}
.reader-content h1 {
  font-size: clamp(1.9rem, 3.4vw, 2.5rem);
  margin-bottom: 0.5em;
}
.reader-content h3 { font-size: 1.18em; }
.reader-content p { margin: 0 0 1.3em; }
.reader-content .science-note {
  background: var(--cream-light);
  border-left: 3px solid var(--sage);
  padding: 18px 22px;
  margin: 2em 0;
  font-size: 0.92em;
  line-height: 1.6;
}
.reader-content .science-note p { margin: 0; color: var(--ink-soft); }
.reader-content .science-label {
  display: block;
  font-family: var(--font-body);
  font-weight: 700;
  font-style: normal;
  color: var(--teal);
  font-size: 0.82em;
  letter-spacing: 0.02em;
  margin-bottom: 6px;
}
.reader-content .section-end {
  text-align: center;
  font-style: italic;
  color: var(--sage);
  margin: 2.4em 0;
}
.reader-content a { color: var(--rust); }

.reader-nav {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 56px;
  padding-top: 30px;
  border-top: 1px solid var(--line);
  max-width: 660px;
}
.reader-nav button:disabled { opacity: 0.35; cursor: default; }

.reader-intro {
  max-width: 660px;
}

@media (max-width: 980px) {
  .reader-shell { grid-template-columns: 1fr; padding: 0 20px 70px; }
  .reader-toc {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    width: min(320px, 84vw);
    background: var(--cream);
    z-index: 60;
    transform: translateX(-100%);
    transition: transform 0.22s ease;
    padding: 90px 24px 24px;
    border-right: 1px solid var(--line);
    box-shadow: var(--shadow);
  }
  .reader-toc.open { transform: translateX(0); }
  .reader-main { padding-left: 0; }
  .reader-icon-btn { display: flex; align-items: center; justify-content: center; }
  .reader-toolbar { top: 0; }
}

.reader-scrim {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(20, 16, 12, 0.4);
  z-index: 50;
}
.reader-scrim.open { display: block; }