.reader-toc-groups {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 0.35rem;
}

.reader-toc-group {
  margin: 0;
}

.reader-toc-details {
  border: 1px solid color-mix(in srgb, var(--border) 85%, transparent);
  border-radius: 0.45rem;
  background: color-mix(in srgb, var(--bg) 97%, var(--text));
}

.reader-toc-summary {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  cursor: pointer;
  list-style: none;
  user-select: none;
  padding: 0.4rem 0.55rem;
  font-size: 0.88rem;
  font-weight: 600;
}

.reader-toc-summary::-webkit-details-marker {
  display: none;
}

.reader-toc-summary::before {
  content: "▸";
  font-size: 0.75rem;
  color: var(--muted);
  transition: transform 120ms ease;
}

.reader-toc-details[open] .reader-toc-summary::before {
  transform: rotate(90deg);
}

.reader-toc-summary-text {
  min-width: 0;
}

.reader-toc-current-mark {
  font-size: 0.86rem;
  line-height: 1;
}

.reader-toc--grouped {
  margin: 0;
  padding: 0 0.75rem 0.55rem 1.65rem;
}