Fonts and Backgrounds

Sorry if this is a question that has been asked and answered. I have daily migraines and light sensitivity is a major problem for me. I know how to change the background in Scrivener to black and the font to white. The problem is when I need to convert it to another format to be able to do a read through on say my kindle I can’t figure out how to convert the entire document back to black text on a white background. Is there a way to do this? It is too much trouble to go through 200+ sections and convert them individually.

Please if anyone knows how to do this pass it along. I have searched the internet to no avail. I am using v1.9.7.0