styling usernames

I was recently looking through other people's sites to try and find inspiration on what I could try style wise and I came across @MentaL's site https://forum.ragezone.com/ They’ve done something really interesting with user banners and names, adding small GIFs to make them stand out more and I...

How can I change the username color and add an icon beside their username in a secondary group? I see something like this but only for the primary group.

I was editing my User Groups and want to style usernames with CSS. But exactly what do I put in this setting? I tried {color:white;} with no effect. Help please!