How to change colour on the top off a webapp on smartphone?

Hello everyone,

I use to “wrap” my fliplet app using “Mobsted’s webapp to PWA wrapper”
This allows me to 2 things :

  1. to have full screen display, just the same way as in fliplet viewer.(non of the upper and lower part of the phone’s button are visible anymore.
  2. as the buttons are hidden, the top and bottom of the page are 100% backgroud colour.

I would like to know if there is a way to change the colour of those upper and lower part when… (some iPhone) users are NOT using… the PWA fullscreen wrapper ? Some users only have the “normal” fliplet webapp (… in standalone). Published fliplet webapps display in “standalone” mode and not in fullscreen (only fliplet viewer is in fullscreen).

The result is that the upper and lower part of the app is white and this is annoying compared to the dark mode background colour off my app (#3d3d3d)

If anyone could tell me if i can change that white colour on the top… Thanks in advance !