为什么tab bar 左侧不显示

<div class="mui-content mui-row mui-fullscreen">
<div class="mui-col-xs-3">
<div class="mui-segmented-control mui-segmented-control-inverted mui-segmented-control-vertical">
<a href="#item1" class="mui-control-item mui-active">列表1</a>
<a href="#item2" class="mui-control-item">列表2</a>
<a href="#item3" class="mui-control-item">列表3</a>
</div>
</div>
<div class="mui-col-xs-9" style="border-left: 1px solid #c8c7cc;">
<div id="item1" class="mui-control-content mui-active">
<p>
内容1
</p>
</div>
<div id="item2" class="mui-control-content">
<p>
内容2
</p>
</div>
<div id="item3" class="mui-control-content">
<p>
内容3
</p>
</div>
</div>
</div>