If you like your apps in a black shade, then Windows 10 allows you to use a dark theme throughout the applications in the operating system. It can be turned on by a simple toggle.
Some apps like the Microsoft Edge web browser will still allow you to change their theme independently regardless of the default app mode that you have specified in Setting. But main apps like Mail, Calendar and the Windows Store shift to a black background when you turn this option on.
This is actually rather handy if you work through the night.
Or have OLED displays on your devices, in which case you can save a lot of battery power, too.
Here’s how you can change the default app mode to a light or dark theme in Windows 10.
1. Open Settings.
2. Click on the Personalization icon.
3. With the Colors option active on the left side on this panel, select your desired dot under the Choose your default app mode heading, either Light or Dark.
4. You will now see a dark theme applied across Windows 10, including pretty much all of the default applications that are included in the operating system. As noted above, some UWP apps will allow you to customize this further on an individual basis.