It appears that the span holding the badges doesn't have a class or any identifier which makes it hard to be able to select it using CSS. Adding a class="badge" would help out a lot.
Usually I would use :not(.nick, .time_stamp, etc.) but it seems OBS has trouble with more complicated CSS selectors.
Additionally it would be nice if the badge span and nick span were part of a parent element like
<div class="display-element"><span class="badges"><img mod /><img subscriber /></span><span class="nick">username</span></div>
But if that doesn't happen I can still hack things together.