.column-list {
  -webkit-column-gap: 2em;
  -moz-column-gap: 2em;
  column-gap: 2em;
  -webkit-column-width: 30ch;
  -moz-column-width: 30ch;
  column-width: 30ch;
}

.collapsed::after {
  content: " ►"
}

.collapsing {
  -webkit-transition: none;
  transition: none;
}