I wasn't suggesting that there'd be anything conscious about the branding, but that it'd be subconscious, so you wouldn't be likely to hear feedback. It's a minor nit, really.

Glad to hear about theming. Flickr/500px/other sites chose to let users opt-in to black backgrounds, I think that is a nice approach - some media is better highlighted by a dark background, but not all. All the best to your project.