Genesis Button Widget Font Color

Hi there! My website is http://www.southerneleganceevents.com

I’d like to change the buttons (inquire, meet us, experience) to be a different color in order to show up better against the photos. I was thinking black. I’ve tried custom CSS adding I found online but just cannot get it to work. Thank you!

Note: NOT the header/top menu, but the buttons below the slide show.
Thank you!