Board Thread:General Discussion/@comment-452-20150306003738/@comment-452-20171005171728

Yes, that's been a feature since April 2015.

To stop it doing that, remove this CSS:
 * 1) gallery-:hover { padding-bottom: 13em; }

edit: Now that I think about it, I'm changing that to 100%, since expanding it to the screen size makes more sense.