On this wiki the headings go berserk in mobile view because of:
.content .mw-parser-output > h1, .content .mw-parser-output > h2, .content .mw-parser-output > h3, .content .mw-parser-output > h4, .content .mw-parser-output > h5, .content .section-heading, .content .in-block { display: table; }
I am not sure where this comes from? Should this be reported and is there a way to prevent this from happening?