Reported here, the correct answers jump to the right of the screen using a custom skin. It’s because the correct answers use the .right class. Changing it to .correct should solve the problem.
Change 445729 had a related patch set uploaded (by Tacsipacsi; owner: Tacsipacsi):
[mediawiki/extensions/Quiz@master] Change CSS class right to correct
Change 445729 merged by jenkins-bot:
[mediawiki/extensions/Quiz@master] Change right to correct and wrong to incorrect