Instant App basemap colors invert when toggling on full screen

[TBWI]

I am working on a Media Map from Instant Apps using the Painterly basemap by John Nelson from Living Atlas. When I toggle on the full screen mode, the colors change pretty dramatically. Is there anyway to prevent this from happening?

     

[KellyHutchins]

This question was initially asked in the Instant Apps forum but this happens in a JS sample too. Here's a code pen https://codepen.io/kellyhutchins/pen/ExMbbLw?editors=1010

[TBWI]

I was able to find a temporary fix for the issue of basemap darkening. I put John Nelson's Blank White Vector Basemap underneath the other layers and it looks normal when toggling to fullscreen. This tells me that fullscreen mode must make the background black so the transparency of the layers causes the darkness to show through.