XF 1.3 Image on post background for one user

[Verringer]

I was wondering if this would be possible, I've seen stuff like it for the original poster and so on - but this would be awesome.

Example of what I want:

If it's not a thing, it should be c:

 

[Jake Bunce]

The concept with an example:

https://xenforo.com/community/threads/various-postbit-colors-by-usergroups.22193/#post-278785

Using that you can apply any CSS styling for specific groups, including background images.