I have implemented the flex-caption using the default CSS rules on my slides successfully, except for a strange issue I am having with Firefox 19 and the transparency of the background color. I have 5 slides and as I move from 1 to 5 the transparency gets less and less opaque, until I get to slide five which pretty much has no transparency. I have tried using a transparent background image as opposed to rgba, but that didn't work either.
Not sure if anyone else is having this problem or if this is a bug. Any information would be appreciated.