Board Thread:Support Requests - Designing Your Wiki/@comment-6038760-20170427175133/@comment-26402117-20170429171857

You could switch off Europa in Special:WikiFeatures to stop the general effect of large elements, and then add this CSS to make it have the same color scheme as the large one and shrink the massive infobox title:

If you want to customize the wiki's infoboxes, you should adopt it and put the CSS you've been given in MediaWiki:Common.css (for Oasis and Monobook).