Custom User Post styling via CSS/Javascript

[teat]

This may not be so much of a request, but more of a point-me-in-the-right-direction sort of thing.

What I'm looking for is a modification that allows administrators to modify post styling for each individual user (or usergroup). These changes would include things like custom background images/colours on posts or background colour change upon hover etc. Im looking for one that does not give the user the option to change said features for themselves, but are changeable for anyone by the admin.

If anyone knows where I could find such a mod, I'd be greatly appriciative!