Hi Alexandre,
Thanks for your help.
I could not find anything wrong with the CSS.
<table class="actionbutton" style="margin: auto;">
<tbody>
<tr class="toprow">
<td style="background-color: #ff6600; border-radius: 6px 0px 0px 0px;"> </td>
<td style="background-color: #ff6600;"> </td>
<td style="background-color: #ff6600; width: 200px;"> </td>
<td style="background-color: #ff6600; border-radius: 0px 0px 0px 0px;"> </td>
</tr>
<tr class="contentrow">
<td style="background-color: #ff6600;"> </td>
<td style="background-color: #ff6600; text-align: center; line-height: 0px;"><a style="cursor: pointer; text-decoration: none; color: #ffffff; font-size: 18px;" href="https://www.vo-nn.nl/voor-leden/in-memoriam" target="_blank" rel="noopener"><img src="media/com_acymailing/calltoaction/call_black4.png" alt="" /></a></td>
<td style="background-color: #ff6600; text-align: center; width: 200px;"><a style="cursor: pointer; text-decoration: none; color: #ffffff; font-size: 18px;" href="https://www.vo-nn.nl/voor-leden/in-memoriam" target="_blank" rel="noopener">Klik hier om te stemmen</a></td>
<td style="background-color: #ff6600;"> </td>
</tr>
<tr class="bottomrow">
<td style="background-color: #ff6600; border-radius: 0px 0px 0px 6px;"> </td>
<td style="background-color: #ff6600;"> </td>
<td style="background-color: #ff6600; width: 200px;"> </td>
<td style="background-color: #ff6600; border-radius: 0px 0px 0px 0px;"> </td>
</tr>
</tbody>
</table>
<p> </p>
<p><a class="jcepopup" href="index.php?option=com_content&view=article&id=1690&user={usertag:username|urlencode}&passw={usertag:password|urlencode}" target="_blank" data-mediabox="1">Klik hier...</a></p>