Lately, it is almost impossible at times to read messages from the user quzah because the text has practically no contrast* to the background. Here's two screenshots that give 3 examples of this and just how hard it is to read:
Screenshot #1 - the black text is easy to make out since the contrast is about 230 or so*, near the maximum possible. The light text is almost impossible to make out as the contrast is less than 10.
Screenshot #2 - The top message here is okay for most of the text, but it's the light-colored text that is very hard to read. The bottom message is the opposite in that almost the entire message is unreadable due to low contrast.
In addition, having the text changing colors very frequently just wastes a lot of space on the server as well. Instead of 1 byte per character, it's almost 25 bytes. The paragraph at the top of this message would use about 4500 bytes just to have the color-changing text. Without the color changing, about 180 bytes would be used instead.
My suggestion would be to enforce a minimum contrast and/or limit the usage of the color UBBCode tag. I would suggest 64 at the very minimum, the difference between the colors BFBFBF and FFFFFF. I would prefer 96 as the suggested minimum, or the difference between 9F9F9F and FFFFFF. I've gone in great depth to finding a worthy contrast-determination formula and I could offer this (and an algorithm based in C) if needed.
* Contrast is based on a comparison of shades of gray of the same apparent brightness. This graph plot gives a good idea on the apparent brightness of each color.
Edit: Just as a side note, no offense is intended. I'm sure this affects everyone. Those with poor vision would really have a lot of problems reading the text which is why I'm strongly suggesting some sort of enforcement.