.sidebar-nav li {
  position: relative;
  margin: 0;
  cursor: pointer
}

.sidebar-nav ul:not(.app-sub-sidebar)>li:not(.file)::before {
  content: '';
  display: block;
  position: absolute;
  top: 17px;
  right: 20px;
  height: 6px;
  width: 6px;
  border-right: 1px solid #8B8B8B;
  border-top: 1px solid #8B8B8B;
  transform: rotate(135deg);
  transition: transform .1s;
}

.sidebar-nav ul:not(.app-sub-sidebar)>li.open::before {
  transform: rotate(-45deg)
}

.sidebar-nav ul:not(.app-sub-sidebar)>li.collapse::before {
  transform: rotate(135deg)
}