This example shows how to set the width of SearchBox to a percentage of its parent container.
<div class="easyui-panel" style="width:100%;max-width:400px;padding:30px 60px;">
<div style="margin-bottom:20px">
<input class="easyui-searchbox" data-options="label:'width: 100%',labelPosition:'top',prompt:'Please Input Value',menu:'#mm'" style="width:100%">
</div>
<div style="margin-bottom:20px">
<input class="easyui-searchbox" data-options="label:'width: 80%',labelPosition:'top',prompt:'Please Input Value'" style="width:80%">
</div>
</div>
<div id="mm">
<div data-options="name:'all',iconCls:'icon-ok'">
All News
</div>
<div data-options="name:'sports'">
Sports News
</div>
</div>