@Shamama 0.815 should be this
.tree-view-item-children {
margin-left: 20px;
border-left: 1px solid rgba(153,153,153,0.5);
border-radius: 5px;
transition:all 0.5s ease-in-out;
}
.tree-view-item-children:hover {
border-left-color: rgba(153,153,153,0.8);
}