Wix Pro Gallery full screen background color

I swear I have done this before, but somehow either the functionality changed or my memory fails me how to do this.

I have Wix Pro Gallery to display some images (masonry mode). When I click on an image, the image opens in full screen mode. The default background color for the full screen mode is puke green. I want to change that to black. I looked all the settings and can’t find a way to change the background color any more. I know it is (or was) possible since I have other Wix Pro Galleries where I have set it in the past to black color. Where is that setting to set the background color of full screen mode images?

In the Gallery settings, try Design > Item Style and scroll to the bottom:

I already tried that and it doesn’t work.