Git master currently uses the destructive css style for the clear button, which makes the button red. While this makes some sense, I don't actually think that it is a good idea:

 * While clear is destructive, it isn't *that* destructive, and you can undo. It doesn't need to be that scary.

 * The red colour is very strong, and draws a lot of attention to the button. This isn't helpful, because it's not the most important/frequently used control, and it distracts from the more important parts of the UI.

The UI would probably be better with the standard button colour for clear.