Awesome, thank you so much! Think that finally did it. I ended up using concatenation to add more classes.
It ended up looking like this:
<?php $bgcolor = get_field('baggrundsfarve'); ?>
<?php $customclasses = $bgcolor . " " . get_field('justering'); ?>
<article id=”post-<?php the_ID(); ?>” <?php post_class('et_pb_post clearfix ' . $no_thumb_class . $overlay_class . $customclasses) ?>>
Out of curiousity, is that the proper way to add a space between the two classes? I mean it works just fine, but I feel like it’s a bit of a MacGyver solution.
