You now have a very own dark-themed look. Here you would have two options: Light and Dark.
Go down till you see the “ choose you app mode” option.In here, loom for the option which sys colors option in the left side panel, click it.After this click on “ personalization”.In the first step, you need to go to “ settings”, either search for this or click on the “ gear icon”, located on the start menu.All you need to do is follow the steps below and get one working like charm: How to Switch Windows 10 Into Dark Mode Without a Theme