/* Categories page accordion */

.matmat-cat-panel {
  overflow: hidden;
  max-height: 0;
  transition: max-height 250ms ease;
}

.matmat-cat-card.is-open .matmat-cat-panel {
  /* max-height set inline by JS for smooth animation */
}

.matmat-cat-toggle .matmat-icon-minus {
  display: none;
}

.matmat-cat-card.is-open .matmat-cat-toggle .matmat-icon-plus {
  display: none;
}

.matmat-cat-card.is-open .matmat-cat-toggle .matmat-icon-minus {
  display: inline;
}