Help Making Chatbox Names Two Colors

I need help to fix this code I found. It should work for the chatbox however i believe it glitched the forum Im trying to create. Can someone help me fix this error.
I believe it goes with this topic: https://help.forumotion.com/t129844-username-in-multiple-colors <--Except that one is just the forum not the CSS for the chatbox.

Code:

span[data-user="#"] { font-size:0 }
span[data-user="#"]:before {
  font-size:11px;
  content:"Name";
  color: black;
}
span[data-user="#"]:after {
  font-size:11px;
  content:"Name";
  color: Color;
}

Sorry for the delay.

Check this:
https://help.forumotion.com/t138440-multi-colored-usernames-in-chatbox

This topic is solved!
Thanks Forumedic