Dark Mode is coming in macOS Mojave, but it doesn't give you a way to write in that kind of environment. You can get that now in Pages if you simply set the background of your document to black and the text to white. Doing this requires the use of Section Masters, a shape, and changing the style for the text. You can then revert to regular colors, or copy and paste text from a dark mode document to a normal one.
▶ You can also watch this video at YouTube.
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▶ Watch more videos about related subjects: Pages (233 videos).
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▶ Watch more videos about related subjects: Pages (233 videos).



You would not want to print pages with black background as it would empty your black ink cartridge in no time
You can reverse the whole screen's colours using ⌃ + ⌥ + ⌘ + 8. So for a white page with black writing, you'd get the same effect: white writing on a black page.
This just toggles on/off