I put together an ayu-based dark theme for rustdoc and Docs.rs a couple months ago, and having now spent a decent amount of time using it and fixing small issues I feel that it’s ready to be shared with the community. The Github repo can be found here. It’s meant to be used via something like Stylish and looks like this:
You can view more screenshots here. If you find any issues or have any critiques to make on my rather poor CSS (or the color scheme itself), don’t hesitate to leave an issue on the repo
EDIT 2/6/17: The style is now on userstyles.org.