This example shows how to assign percentage width to a column in TreeGrid.
<table title="Fluid Browser" class="easyui-treegrid" style="width:700px;height:250px"
data-options="
url: 'examples/treegrid/treegrid_data1.json',
method: 'get',
idField: 'id',
treeField: 'name'
">
<thead>
<tr>
<th data-options="field:'name'" width="50%">Name(50%)</th>
<th data-options="field:'size'" width="20%" align="right">Size(20%)</th>
<th data-options="field:'date'" width="30%">Modified Date(30%)</th>
</tr>
</thead>
</table>