This could be a work around, though it doesn't have all the same functionality as the local Windows Program/App.
In Chrome, Use the Menu > More Tools > Create Shortcut for when logged in to your web account (might need to quickly create the shortcut while the page is loading for https://www.evernote.com/Home.action instead of the generated link for the note at the top of the side column list).
Select Open as Window.
Shows up on your desktop and in the Apps Tab as Evernote Web.
Then add a dark mode reader for Chrome like Dark Reader.
Customize colors as desired.
**works on Google Docs also.**
If you want to try something different for a change, install f.lux and enable Darkroom Mode.