I found the solution. This code works:
code $("[name=mgc5]").css("background-color", "#CC0000"); /code
The problem is that I need to execute it for every item returned from the Facebook API. So I can call the REST from the custom JS, how can I update the correct UI element when each REST request returns its correct value?
Thanks Maryna, that's exactly as I wanted.
How can I add that?
I try to add it as "add property" and also as CSS, but both don't work for me.