I would like to make a table with one row (header for all columns) and then with rows and cols below header (just a regular table after the header). I have something like this for now on:
<table style="margin: auto;" border="1">
<colgroup>
<col align="left">
<col align="right">
<col align="right">
<col align="right">
<col align="right">
<thead style="background: #F0F0F0" colspan="6" scope="colgroup">
<tr>
<th>header
<thead style="background: #F0F0F0">
<tr>
<th>a
<th> a
<th> a
<th> a <br> b
<th> a
<th> a
</table>
but now, 'header' is in the first column only and I would like it to be stretched for all columns.