Background picture Grid row does not scale according to contain"

Hi,

I tried to make the same design as https://kriesi.at/themes/enfold-app/. with the scroll sliding option. I have tried different sizes, different amounts of whitespace in the png, different positions inside the grid row cell but if the screen side is moved sideways it does not scale but move under the cell on the right side. The idea of “contain is that the entire picture is always vissible, correct?
it also look really bad on ipad landscape

The link of the page is https://lightside.nl/webdesign-den-haag/

Please assist

kind regards
Gerrit