If you want to get involved in making Simple.css better, please feel free to submit a pull request with any additions or changed you think would be suitable.
Alternatively, if you're not a coder, or don't want to submit a pull request, feel free to submit an issue.
If you decide to contribute to this project, please edit the simple.css, once I merge your change, I will minify it myself.
If you do add contributions, please add verbose commenting so I can understand the rationale for the changes/additions you are proposing.
Thanks again for wanting to contribute to this project!
-- Kev