Button Hover Text Color

Hi, I'm working in Clean Education Pro and need help with the Button Hover Text Color for the Hero Content. I'm setting it to white in the same way as I do for the Featured Sliders Button Hover Text, but it does not show. I can change it to any other color and it changes, but not to white..... The weird thing is that it works for the Featured Sliders but not Hero Content... A bug in the system or what am I missing? The site I'm working on is www.gestaltkurser.se Thanks for any help! Monica