纯css实现属性结构

**css实现属性结构的思路是利用伪类实现树形结构连接线，如果想实现点击展开和收缩以及复选框效果还得配合js来实现。其实展开和收缩就是一个点击元素其子元素隐藏和显示的切换。**

效果图

html结构

 <ul class="domtree"> <li> 1级菜单 <ul> <li>2级菜单</li> <li> 2级菜单 <ul> <li>3级菜单</li> <li>3级菜单</li> </ul> </li> </ul> </li> <li> 1级菜单 <ul> <li>2级菜单</li> <li>2级菜单</li> </ul> </li> </ul>

css

 ul.domtree, ul.domtree ul { margin: 0; padding: 0 0 0 2em; } ul.domtree li { list-style: none; position: relative; } ul.domtree>li:first-child:before { border-style: none none solid none; } ul.domtree li:before { position: absolute; content: ‘‘; top: -0.01em; left: -0.7em; width: 0.5em; height: 0.615em; border-style: none none solid solid; border-width: 0.05em; border-color: #aaa; } ul.domtree li:not(:last-child):after { position: absolute; content: ‘‘; top: 0.7em; left: -0.7em; bottom: 0; border-style: none none none solid; border-width: 0.05em; border-color: #aaa; }