Thread:MaxiGamer WiiU/@comment-26447184-20150707022113/@comment-25801460-20150707035236

chat.css is basically the CSS (the look) of the chat. If you go at User:(Your username)/chat.css, you can create it and put CSS code on it.

What's cool with this, is that this CSS will only change what YOU see, and not what everyone else sees, which is very convenient for when you wanna test CSS before adding it to the real Chat.css.