This is fantastic. I woke up one day to find the most hideous colors in back of my tabs. Not in the tabs, but behind them. Don't know why that happened. After some googling, came across Clear Transparent Glass. Not only did it eliminate the colors, it has been impact-free on Firefox: no ripple effects, no distortions, nothing. As opposed to Simple White, which squared off my tabs and had other unwanted effects. Clear Transparent Glass is a wonderful theme if you are looking for a plain background or if you are not happy with the colors being foisted on you.