Mobile slider problem

Hello, I’d like some help in making my front page more mobile friendly.
On smaller devices (experienced on mobiles and some tablets), the text of the front page slider disappears.

I assume this problem originates from the text and the button having a fixed size, and the slider image having a device-sensitive size. However, I am not very good on css and I have no idea how to fix this.

Is there someway I could add a something in css to make the height of the slider larger or the text/button smaller?

Any help is much appreciated
https://totalimmersionenglish.org/
Openstrap version: 1.0.7

p.s. @pavan thanks for you time on making this theme. It’s a real work of art!