White background black font or black background white font?

Question

Design

For some reason, all sites are made on a white background. But on a dark background, the eyes get tired less. Why then is the dark background almost never used?

Answer 1

But on a dark background, the eyes get tired less

It's a delusion. Constantly reading light text on a dark background will lead to health problems. You need to read dark, contrasting text on a light background and in good lighting (yes, we are still talking about working at a computer).