Button disappears from Revolution Slider on mobile

Hi,

I am using the same slider as in the demo (http://hb-themes.com/themes/highend_wp/home-example-2/). Classes for the button are hb-button hb-second-light

The buttons disappear when accessed on mobile devices.

I tried disabling the responsiveness for that layer by un-ticking the option “Responsive Through All Levels” under “Advanced Responsive Settings” in “Layer Links & Advanced Params”.

Is there a custom css code that I can add to solve this issue?

Thanks