There is an overlay of the two buttons on my site when I minimize the window resp. when I open the page on a tablet. The overlay always happens on a screen width of 1016 px.

I already inserted a margin and padding but it does not seem to effect the result.

Thank you for your help!

page: http://www.espros.com (buttons on startpage)

I see, the cols are way too small at responsive mode (tablet size) so the buttons overlap.
Try fixing this with the Responsive Mode options when editing each of your columns!
You can set its behavior for the corresponding device!