Depressed buttons are in need of some Xanax? ;) But seriously I'm not sure what you mean here. I don't think the active state should be using white fg, but that's probably not what you mean here?

Created attachment 279620 [details]
active state for popover buttons

Created attachment 279627 [details]
this is what I'm talking about

Something like this:

.popover .button:active {
  border: none;
  background: none;
  box-shadow: none;
}

fixes it

*** Bug 729023 has been marked as a duplicate of this bug. ***

the snipped will flatten up all button inside the popover, it needs something a bit more complicate, the problem is that the button label doesn't change its color wrt states