If I change the color hue of all the CSS variables from green to red, and make the text a bit darker and larger it's not so bad. With a light gray background on the sidebar to provide some contrast with the main content like the Rust doc does I quite like it.

I'll probably create custom CSS rules for the doc if this is the final version and be happy with it. I've been using a custom dark theme for HN for years and I'm happy with it. I'm glad we still have enough control over web pages to do that!