Microsoft's Dark Mode support in Office was just really just the start of a much larger (and darker) trend. The software giant has started rolling out Dark Mode to its Outlook mobile apps on Android and iOS, not to mention Office.com. There's not much mystery to how it works -- surprise, it's darker -- but it should go a long way toward reducing eye strain when you're checking email on the bus home or finishing a project late at night. It should extend battery life on devices with OLED displays, too.