font size responsive options in revslider

Hi,

I have a slider in the homepage header. When I decrease the side of the browser’s window to see how the site looks on mobile, the size of the font get smaller to fit the screen, but at the lower size, it becomes big again and then the sentence is cut by the window et the left and at the right. I’ve tried to play with the css but can’t find where I should change that. All the other pages where there are no slider works fine, so I suspect this is a revolution slider issue.
Do you have any idea how to solve this?
Thanks a lot for your help