Move #crtlbar styles out of #viewframe

There’s no need to force selectors so deeply. Eventually, I’ll go through everything and ease up on scoping everything to its parent/s. For now, it made sense to separate #ctrlbar just to get it out of the way, but it should be done throughout.
Style video player

Dark background, large player without padding, plus extra class for obscuring the video player while the assetlist is expanded.
Obscure videoplayer (opacity/blur) when assetlist is expanded