Sindbad~EG File Manager

#nav-drawer {
  .metismenu {
    .collapse {
      display: none;
    }

    .collapse.in {
      display: block;
    }

    .collapsing {
      position: relative;
      height: 0;
      overflow: hidden;
      transition-timing-function: ease;
      transition-duration: .35s;
      transition-property: height, visibility;
    }

    .has-arrow {
      position: relative;
      cursor: pointer;
    }

    .has-arrow::after {
      position: absolute;
      content: '';
      width: .5em;
      height: .5em;
      border-width: 1px 0 0 1px;
      border-style: solid;
      border-color: initial;
      right: 1em;
      -webkit-transform: rotate(-45deg) translate(0, -50%);
      transform: rotate(-45deg) translate(0, -50%);
      -webkit-transform-origin: top;
      transform-origin: top;
      top: 50%;
      transition: all .3s ease-out;
    }

    .active > .has-arrow::after,
    .has-arrow[aria-expanded="true"]::after {
      -webkit-transform: rotate(-135deg) translate(0, -50%);
      transform: rotate(-135deg) translate(0, -50%);
    }
  }
}