Need unique color posts for predefined users

[ondas]

Hi, can anyone tell me, if it is somehow possible to have:

for a predefined set of users (either defined manually or in a group, doesn't matter), the background of the post would be in a different color. So for example if the standard background of the post is blue, for some users the standard would be set to green. Users themselves should'nt have the ability to change the background (so that they couldn't be mistaken).

Is it possible to find such modification somewhere?

[ondas]

Or maybe not the whole background, but just different text color - is that possible?