如何调整Jquery Easyui, tab的宽度

[待解决问题]

如图，使功能菜单的宽度与下边的west宽度相同。样式为easyui metro-blue.

代码如下：

    <div class="easyui-layout" fit="true">
        <div data-options="region:'north',split:true,collapsible:'false'" title="aa"   style="height:50px"></div>
        <div data-options="region:'south',split:true" style="height:50px;"></div>
        <div data-options="region:'east',split:true" title="East" style="width:180px;"></div>
        <div data-options="region:'center',iconCls:'icon-ok'">    
        <div class="easyui-tabs"  fit="true">
        
        <div  title="功能菜单">
        <div class="easyui-layout" fit="true">
            <div data-options="region:'west'" title="west" style="width:180px;"></div>
            <div data-options="region:'center',iconCls:'icon-ok'">
            
            </div>
        </div>
        </div>
        <div title="My Documents" style="padding-left:100px">
            <ul class="easyui-tree" data-options="url:'tree_data1.json',method:'get',animate:true"></ul>
        </div>
        <div title="Help" data-options="iconCls:'icon-help',closable:true" style="padding:10px">
            This is the help content.
        </div>
    </div>
            
    </div>
</div>