<table>
<thead>
<tr>
<!-- daca aici am 3 coloane -->
<th></th>
<th></th>
<th></th>
</tr>
</thead>
<tbody>
<tr>
<!-- si aici am 3 coloane -->
<td></td>
<td></td>
<td></td>
</tr>
</tbody>
</table>
<!-- ca sa repari layoutul tau -->
<table>
<thead>
<tr>
<th></th>
<th></th>
<th></th>
</tr>
</thead>
<tbody>
<tr>
<!-- aici folosesti un colspan 3, pentru ca in head ai 3 coloane, extinzi celula asta pe toate 3, apoi bagi tabelul in ea -->
<td colspan="3">
<!-- ... -->
</td>
</tr>
</tbody>
</table>