Bug 1049198 - Camera/Video should use mark Color layer as [not visible] ...

...when covered by video
Was this why the hud was overflowing the screen?
Won't these changes affect the position of the buttons since you're removing the negative margin but only reducing the border size by a little bit?  I assume the transparent border is to increase the touch-sensitive area?

Rather than removing the margin property entirely, could you modify it for each of the individual buttons so that it is the right amount on each side without overflowing?