editing "main color" in gridmarket

I'm using gridmarket as the child theme for frame market. I want to change the main text color for links to be different from the color that serves as the background to the header. These color settings seem tied together as "main color" which I can change through theme options. So if I make it white, which I want the background to be, the text is white too and doesn't show up. How can I change this?
Thanks for your help!