Rated 4 out of 5 stars
Good addon, but need an update to fully compatible with Fx20 (new shadows, opened menu color setting, private browsing mode color setting etc...)This review is for a previous version of the add-on (0.8.1-signed).
I just tested the open colour by setting "background: red;", and hover colour by setting "background: magenta;" in the general tab, and both work as expected (FireFox 20.0.1). Please can you explain how it isn't compatible for you in more detail?
When version 0.81 passes review, you'll have the ability to easily change the style as applied to private browsing from about:config.