Forum:Help with CSS

Hi. I need some help with my global.css on another wiki, I am an admin there, and I am trying to make blog comments by admins a different color and say @Admins. There is an example on the 39 Clues Wiki, there admins have it. I have been trying, but it does not work. Here is the link:

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If someone would help me, or even do it for me it would be much appreciated.