Hi, thanks for getting back to us!
Not sure I understand you correctly. The only way to change it to full width over there is to select ‘No Sidebar, full width”. I did try that even though we want to keep our sidebar, but it’s still not full width, the posts below it stick out on both sides.
If it helps, this page has the same template and the right width:
https://hacweekblad.nl/kalender/
To clarify, this is what I’m trying to align:
