无限级树状图ｃｓｓ实现

<style>
    .tree{
        1000%;
    }
    .tree ul {   
    padding-top: 20px; position: relative;
    transition: all 0.5s;
    -webkit-transition: all 0.5s;   
    -moz-transition: all 0.5s;   
    }
   
.tree li {   
    float: left; text-align: center;   
    list-style-type: none;   
    position: relative;   
    padding: 20px 5px 0 5px;   
       
    transition: all 0.5s;   
    -webkit-transition: all 0.5s;   
    -moz-transition: all 0.5s;   
}   
   
/*We will use ::before and ::after to draw the connectors*/   
   
.tree li::before, .tree li::after{   
    content: '';   
    position: absolute; top: 0; right: 50%;   
    border-top: 1px solid #ccc;   
     50%; height: 20px;   
}   
.tree li::after{   
    right: auto; left: 50%;   
    border-left: 1px solid #ccc;   
}   
   
/*We need to remove left-right connectors from elements without    
any siblings*/   
.tree li:only-child::after, .tree li:only-child::before {   
    display: none;   
}   
   
/*Remove space from the top of single children*/   
.tree li:only-child{ padding-top: 0;}   
   
/*Remove left connector from first child and    
right connector from last child*/   
.tree li:first-child::before, .tree li:last-child::after{   
    border: 0 none;   
}   
/*Adding back the vertical connector to the last nodes*/   
.tree li:last-child::before{   
    border-right: 1px solid #ccc;   
    border-radius: 0 5px 0 0;   
    -webkit-border-radius: 0 5px 0 0;   
    -moz-border-radius: 0 5px 0 0;   
}   
.tree li:first-child::after{   
    border-radius: 5px 0 0 0;   
    -webkit-border-radius: 5px 0 0 0;   
    -moz-border-radius: 5px 0 0 0;   
}   
   
/*Time to add downward connectors from parents*/   
.tree ul ul::before{   
    content: '';   
    position: absolute; top: 0; left: 50%;   
    border-left: 1px solid #ccc;   
     0; height: 20px;   
}   
   
.tree li a{   
    border: 1px solid #ccc;   
    padding: 5px 10px;   
    text-decoration: none;   
    color: #666;   
    font-family: arial, verdana, tahoma;   
    font-size: 11px;   
    display: inline-block;   
       
    border-radius: 5px;   
    -webkit-border-radius: 5px;   
    -moz-border-radius: 5px;   
       
    transition: all 0.5s;   
    -webkit-transition: all 0.5s;   
    -moz-transition: all 0.5s;   
}   
   
/*Time for some hover effects*/   
/*We will apply the hover effect the the lineage of the element also*/   
.tree li a:hover, .tree li a:hover+ul li a {   
    background: #c8e4f8; color: #000; border: 1px solid #94a0b4;   
}   
/*Connector styles on hover*/   
.tree li a:hover+ul li::after,    
.tree li a:hover+ul li::before,    
.tree li a:hover+ul::before,    
.tree li a:hover+ul ul::before{   
    border-color:  #94a0b4;   
}   
</style>

<ul>
    <li>
        <a href="#">Parent</a>
        <ul>
            <li>
                <a href="#">Child</a>
                <ul>
                    <li><a href="#">Grand Child</a></li>
                </ul>
            </li>
            <li>
                <a href="#">Child</a>
                <ul>
                    <li><a href="#">Grand Child</a></li>
                    <li>
                        <a href="#">Grand Child</a>
                        <ul>
                            <li><a href="#">Great Grand Child</a></li>
                            <li><a href="#">Great Grand Child</a></li>
                            <li><a href="#">Great Grand Child</a></li>
                        </ul>
                    </li>
                    <li><a href="#">Grand Child</a></li>
                </ul>
            </li>
        </ul>
    </li>
</ul>