RoksSproket Tabs module formatting

HI. I'm using the RoksSproket component with Expert template in Joomla and am having trouble with the formatting of Tabs-based module in the template. The box text colour I am using is white and the tab is also white, so the title cannot be read. I have tried making changes in Customizer for Primary Box colours which I am using, but can't seem to affect the tab itself. Any help would be gratefully received!

Please analyze the css class and put an override to your css/custom.css for the tabs
www.joomlaplates.com/template-customizing

Thanks for this - I'm not really into coding CSS but will see if it's something I can handle!