/* Stack: modalità + lingua richiudibili (preferenza salvata) */
html[data-shell="stack"] .study-opts-toggle {
  width: 100%;
  margin: 8px 0 4px;
  min-height: 44px;
  border-radius: 14px;
  border: 1px solid color-mix(in srgb, var(--card-ink, #eee6d4) 18%, transparent);
  background: color-mix(in srgb, var(--pane, #323028) 92%, transparent);
  color: var(--card-ink, #eee6d4);
  font-size: 13px;
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 0 14px;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

html[data-shell="stack"] .study-opts-toggle .study-opts-chevron {
  opacity: 0.65;
  font-size: 12px;
  transition: transform 0.15s ease;
}

html[data-shell="stack"] .study-opts-toggle[aria-expanded="true"] .study-opts-chevron {
  transform: rotate(180deg);
}

html[data-shell="stack"] .study-opts-panel.is-collapsed {
  display: none;
}

html[data-shell="stack"] .study-opts-panel {
  margin-bottom: 4px;
}