First you need to use jquery to identify whether your table body content have scrollbar or not. Next you need to toggle one class with the calculation of adding scrollbar width. So here is the solution with that.
HTML
<table class="tableSection">
<thead>
<tr>
<th><span class="text">album</span>
</th>
<th><span class="text">song</span>
</th>
<th><span class="text">genre</span>
</th>
</tr>
</thead>
<tbody id="mytest">
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td> </tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td> </tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
<tr>
<td>td</td>
<td>td</td>
<td>td</td>
</tr>
</tbody>
</table>
CSS
table.tableSection {
display: table;
width: 100%;
}
table.tableSection thead, table.tableSection tbody {
float: left;
width: 100%;
}
table.tableSection tbody {
overflow: auto;
height: 150px;
}
table.tableSection tr {
width: 100%;
display: table;
text-align: left;
}
table.tableSection th, table.tableSection td {
width: 33%;
border: 1px solid #ccc;
}
.extrawidth{
width:calc(100% - 18px) !important;
}
JQUERY
(function($) {
$.fn.hasScrollBar = function() {
return this.get(0).scrollHeight > this.height();
}
})(jQuery);
$(document).ready(function(){
if($('#mytest').hasScrollBar())
{
$('.tableSection thead').toggleClass('extrawidth');
}
});
Have a Fiddle Demo