This won't work because the forum-based font color works as a stand-in for the chatbox, the black color in the CB doesn't actually work. If you try to use it, it'll come out as a light color
However, if you type in what's necessary to change the color to black in the chatbox
It'll come out like this (bolded to be easier to read)
However, if you type in a certain color #, you can make it look like this:
Invisible? I think not.
(highlight it in order to read it)
This has nothing to do with the list of chatbox colors, but everything to do with the use of the code in forum posts and chatbox posts.