Dark theme can help reduce eye strain. It displays the system background and supported apps in black. 
	 
 
  
- 
From the 
				Home screen, tap 
				. 
			 
- 
Tap the 
			 Dark theme
On/Off switch to turn it on or off. 
		  
Note: When 
		  
Battery Saver mode is on, your phone also turns on 
		  
Dark theme automatically. See 
		  
Using 
	 Battery Saver mode for details.