This is your style problem because I have also same problem and fixed by style developer. Do you have issue with xenforo default style?
This styles issue and get response from styles developer.
We have an option to replace all of the banners in XenForo which use our custom properties. By doing so we remove a specific code that isn't required and that's causing the problem here. We can leave that code in and not cause any conflict, so you don't need to alert the developer of the add-on, we'll fix it on our level next release. Next patch you can just revert the changes I posted above.