Background of enlarged images is blinding white?

So I've build my website in Adobe Portfolio, everything is nice and dark. But any time I click an image in my photo grids to view it, the image is enlarged and the screen is blinding white, it is extremely jarring. 

I don't see any options at all that relate to this in the photo grid settings, and the page settings for background colour are just for the normal site page view. 

How can I change this? It is unpleasant to view the site as it is.