When using the DSi version of chatrooms, there's a number of things wrong.
Firstly, it says "3DSPaint Chatroom" in the title. Minor thing.
Secondly, the panels are too tall (copied from the 3DS version, it seems), so there is a little bit of scrolling necessary to see certain things. Minor thing.
Thirdly, the background is white if it's dark mode, which means there's light grey text on white. Text is usually unreadable. Not so minor thing. Still an easy fix though.
@BLACK_OPS if there's no chatroom directory in DSiPaint, then the 3DS Paint one is all you'll need to change since those pages are ported over to DSiPaint automagically
I cannot find the "chatroom" directory in the dsipaint.com folder, unfortunately, but I made the changes on the 3DSPaint side like including the chatroom name in the Chat, I know that only fixes one thing haha, but I'll figure it out :p