.folder-icon {
    height: 20px;
    width: 20px;
    margin-right: 5px;
}
li {
    line-height: 1.3;
    list-style-image: none; /** prevent inheritance if inside folder **/
}
.li-folder {
    list-style-image: url('folder.svg');
}
.li-folder.li-folder-open {
    list-style-image: url('folder-open.svg');
}
.hidden {
    display: none;
}
.selected {
    background: rgba(255, 0, 0, 0.5);
}