Ever figured it out? https://www.mediawiki.org/wiki/Help_talk:Images
Topic on User talk:Libattery
Appearance
Add
div.thumb { float:none !important;}
div.thumbinner { margin: 0px auto !important;}
to mediawiki:Common.css
Add
div.thumb { float:none !important;}
div.thumbinner { margin: 0px auto !important;}
to mediawiki:Common.css