- setting firefox theme to dark
 - using an extension to force sites that do not implement user-prefers-color-scheme to be dark themed.

Sites such as startpage.com, google, youtube and others implement the `user-prefers-color-scheme` css system for light and dark themes. This often takes the form of a dropdown selection with options light, dark, and system-setting. On Linux, firefox, with a Mate desktop, I have set firefox theme and my window manager to dark. This is not being passed to the end site. Unable to identify the value they are presenting a light theme. My windows is light themed with a dark themed firefox. Firefox does not tell google (and other) sites that I'm interested in the dark theme. Is there a way to always set the css level variable of user-prefers-color-scheme to dark? Most answers in this space are referring to: - setting firefox theme to dark - using an extension to force sites that do not implement user-prefers-color-scheme to be dark themed. Instead I'm interested in setting that value to always request dark theme from sites that implement dark themes and accepting light themes from sites that do not implement dark themes. Interestingly this is not set by firefox dark themes in my cases, perhaps there is an underlying bug or unexpected behavior in how that is calculated in my cases?