Help with altering responsive CSS for mobile view please

I’m redesigning the services images on the front page on a companies website.

I am using Jupiter template in WP. WP bakery allows me to display two columns side by side in desktop mode with css “.wpb_content_element{width:50%}”

I want to maintain this in mobile and have tried every way that I can think of, but I cannot get the change to apply.

DESKTOP VERSION
image

Any help appreciated. Thanks!

Website is: