h4
  cursor: pointer
  &:after
    content: "▸"
    font-size: 0.8em
    margin-left: 10px
    transition: transform 0.2s

  &.active:after
    transform: rotate(90deg)

div.outline-text-4
  display: block

  .playlist, .notes, .contents
    display: none

    &.active
      display: block