prism-js-fold.scss

code {
  details {
    &[open] {
      & > summary > span:first-child::before {
        transform: rotate(90deg);
      }
    }
    &:not([open]) {
      display: inline;

      & > summary::after {
        content: ' ... '
      }

      & + span.ll {
        display: none;
      }
    }
  }

  summary {
    display: inline;
    position: relative;
    list-style: none;

    & > span:first-child::before {
      position: absolute;
      display: inline-flex;
      align-items: center;
      height: 21px;
      margin-left: -16px;
      margin-top: 1px;
      content: "▶";
      font-size: 12px;
      font-style: normal;
      transition: transform 100ms;
      color: #999;
    }
  }
}