Email column background to fit width

Hi,
I am trying to add background to the email column. I want to see the whole width of the image, but it always stretches it to cover the whole block.
I tried to change background-size to contain in the additional css, but it is not working.
I used this css:
.viwec-block .viwec-layout-row { background-size: contain!important;}

Can you advice?
Thanks