结构图HTML代码

<div class="tree">
    <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>
</div>

CSS

.tree {
    width: 760px;
    margin: 40px auto 0 auto
}.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;
    width: 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;
    width: 0;
    height: 20px;
}