Change color

The event’s inherit the colour of the categor(ies) to which they are designed. The text colour is to chosen in such a away to ensure readability. Both can be filtered using this hook: https://codex.wp-event-organiser.com/hook-eventorganiser_fullcalendar_event.html

I have a black background with white text on my site. I cant see the calendar dates because the text is in white with a white background. How can I easy change the white calender text to black? Can I change any calendar CSS ?

Lars