Microsoft Edge has a dark theme, but you have to enable it in Edge’s application settings. Even if you enable Windows 10’s dark theme, Edge will keep using its light app mode until you go out of your way to select dark mode.
Steps to enable dark mode in Microsoft edge.
To enable the dark theme in the new, Chromium-based Microsoft Edge browser, click the menu button and select “Settings.”
Select the “Appearance” category on the left side of the Settings page.
Under customize browse, click on “Theme” box and select “Dark.”
By default, Edge is set to the “Light” theme. You can also select the “System default” option and Edge will follow the Windows theme option you chose in the Settings app.
How to enable dark theme on all web pages.
Websites can choose to obey your browser’s dark theme, but almost no websites actually will yet. The new Edge browser is based on Chromium, however, and contains the same experimental “force dark mode” option found in Google Chrome.
To enable it, type “edge://flags” into Edge’s address bar and press Enter.
Search for “Dark Mode” in the search box at the top of the Experiments page. Click the “Force Dark Mode for Web Contents” box and select “Enabled.”
When you’re done, click “Restart.” Microsoft Edge will close all your open Edge browser windows and reopen them. You won’t lose your open tabs, but be sure you’ve saved any work (such as data entered in forms) on the web pages before continuing.
Browse around and see how it works. You can disable this option by heading back to the Flags page, setting the “Force Dark Mode for Web Contents” option to “Default,” and restarting Edge once again.