How to change background color of page to black but remain it white for printing in LibreWriter?

[I already did this once way time ago- so I do not remember how to repeat this]

I recently inserted my own custom palette to

C:\Program Files\LibreOffice\share\palette

thus wanted to apply its colors to my documents. I can go to

Format > Page Style > Area > Color > Palette > [MY CUSTOM PALETTE]

and choose a color for a background - so far so good. But when I now press CTRL + P I see black page instead of white- like I used to

I need to see white text on black background when I write and read on screen- and black on white when read on paper what I print out

See similar question asked 15 hours ago, i.e. rather close to the top in the list. You should have browsed a bit the site.