Board Thread:Support Requests - Designing Your Wiki/@comment-32718477-20171121231326/@comment-26478829-20171122032110

The simplest solution would probably be to edit your infobox .css. Importing this into your MediaWiki:Common.css seems to do the trick.

.portable-infobox .pi-title { color: white; background-color: #000; }

Where "white" is, you put in the color you want the text to be, where "000" is, you put the bg color. Here's a list of hex colors if you need to get precise.