Per-Group Postbit Background

[SirMarcum]

What i'm trying to accomplish is having the ability to add a background image/color to the postbit PER group.
IE Admin = Red, Mod = Gold, Donator = Pink, etc. See example below.

As it stands, I could add this custom CSS to the entire site and override the default css by changing the following CSS to the custom css field of my template.

I'm wondering if this can be accomplished in similar fashion to either Username CSS or badge css.

.forum-left-col {
padding: 2rem 1.25rem;
border-right: 3px solid rgba(255, 255, 255, 0.03);
background: url(https://i.imgur.com/kOU7pmX.png);
height: 100%;
}

[SirMarcum]

Also to add, another option for post-body background per-group would be amazing as well. Example:

I know the CSS to be editted to make this happen, just not the know-how on being able to set it per-group.