html-table-length which length (choice the largest)

<colgroup>
<col span='1' style='width:1px;min-width:50px' > <!-- header.delete.mark -->
<col span='1' style='width:5.0em;'/>
<col span='1' style='width:50.0em;'/>
<col span='1' style='width:12.0em;'/>
</colgroup>

<tr style="font-size:12px;height:18px;" >

<th style='width:10px; bgcolor=lightgrey;'>_</th>

<th style="width:5.0em;" bgcolor="lightgrey">
<div style="text-overflow:ellipsis;width:5.0em;">
ITEM NO
</div>
</th>

<th style="width:50.0em;" bgcolor="lightgrey">
<div style="text-overflow:ellipsis;width:50.0em;">
DESCRIPTION
</div>
</th>

<th style="width:11.0em;" bgcolor="lightgrey">
<div style="text-overflow:ellipsis;width:8.0em;">
_
</div>
</th>

</tr>
</TABLE>