.ExpandableToolbarButton:hover .ExpandableToolbarButton__arrow:after {
  content: "";
  position: absolute;
  bottom: -10px;
  border-width: 10px 10px 0;
  border-style: solid;
  border-color:#5acce6 transparent;
}

.ExpandableToolbarButton .ExpandableToolbarButton__content {
  display: none;
}

.ExpandableToolbarButton:hover .ExpandableToolbarButton__content {
  display: block;
}