В новой Mac OS Mojave (10.14) добавили темный режим. Я неделю поработал в нем, но потом отключил. И вот в чем причина: https://ux.stackexchange.com/questions/53264/dark-or-white-color-theme-is-better-for-the-eyes#53268

> However, most studies have shown that dark characters on a light background are superior to light characters on a dark background (when the refresh rate is fairly high). For example, Bauer and Cavonius (1980) found that participants were 26% more accurate in reading text when they read it with dark characters on a light background.

...
> People with astigmatism (approximately 50% of the population) find it harder to read white text on black than black text on white. Part of this has to do with light levels: with a bright display (white background) the iris closes a bit more, decreasing the effect of the "deformed" lens; with a dark display (black background) the iris opens to receive more light and the deformation of the lens creates a much fuzzier focus at the eye.

Темные буквы на светлом фоне читаются лучше чем светлые на темном. Мои субъективные ощущения это подтверждают (когда темная тема включена я делаю больше опечаток, которые замечаю позже).