https://finance.yahoo.com/news/macos-mojave-sweet-small-surgical-upgrade-170005249.html

Herewith: A list of what’s new, with a letter grade for how good it is.

General. Once you turn it on, most of Apple’s built-in apps—Finder, Mail, Calendar, Messages, iTunes, Notes, Xcode, and so on—match that white-on-black appearance." data-reactid="16">Dark Mode is a dark-gray color scheme; you’re offered the chance to turn it on during the installation process, and you can turn it on and off at will in System Preferences -> General. Once you turn it on, most of Apple’s built-in apps—Finder, Mail, Calendar, Messages, iTunes, Notes, Xcode, and so on—match that white-on-black appearance.