Yup, this is what I was looking for. Other extensions I tried didn't work for what I needed. This one seems to toggle the light/dark on specific types of panels in the browser. So, thanks for the fix.

Love it! It does exactly what I needed it to and toggles the CSS @media (prefers-color-scheme: ) between light and dark. Great for testing websites during the development phase or changing a website's mode without changing the whole browser.

Good job. It would be even greater if one could store websites that should be "always dark" and "always light" but nevertheless: simple and effective extension. Thanks!