View in HD at . 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.