ul.simple-tree{padding:0;margin:0}ul.simple-tree ul{padding-left:2em}ul.simple-tree li{list-style-type:none}ul.simple-tree li>.tree-icon{display:inline-block;width:1.5em;margin:2px;background-color:#eee;text-align:center;cursor:pointer}ul.simple-tree li.tree-opened>.tree-icon:after{content:"-"}ul.simple-tree li.tree-closed>.tree-icon:after{content:"+"}ul.simple-tree li.tree-empty>.tree-icon{visibility:hidden}