when i enlarge- gallery item -- LightBox background color is always light grey?

 when i enlarge- gallery item -- LightBox background color is always light grey? i have tried css changes.  I just want the lighbox background to match the darker background when i enlarge it. 

https://ocelot-potato-5w8l.squarespace.com/config/pages/5f2aeac7e085e460bd9586e7

www.othart.com/cp1

I have tried the following other threads that use lightbox CSS and they didn't work. I think its its because I'm not using it inside of a block.

something is using an overlay color and throwing a wrench into things.

OMG! thank you so much for this!

7 hours ago, othbot said:

OMG! thank you so much for this!

Not a problem!