Dashboard-Font unreadable

Hello,
GamePress is a very nice theme and I would also like to upgrade to pro version. But since a few weeks, I have the problem that the font in the dashboard is no longer readable. The font is white with a blurred outside line. The background is also white. This condition was only after an update a few weeks ago. Where or how can I change the font type. Unfortunately, I am a beginner. About some help I would be very happy.