Исправлена высота таблицы HTML
<div id="mainHolder" style="overflow: auto; max-height: 400px;">
<table>
... Lots of data ...
</table>
</div>
MRLSK8
<div id="mainHolder" style="overflow: auto; max-height: 400px;">
<table>
... Lots of data ...
</table>
</div>
<table style = "width:100%">
<tr>
<th>A</th>
<th>B</th>
<th>C</th>
</tr>
<tr>
<tb>a</tb>
<tb>b</tb>
<tb>c</tb>
</tr>
</table>