Rated 5 out of 5 stars

Thank you. This did affect the color of my toolbar (I use Nuvola theme), but it just makes for a better separation of the toolbars/tab bar. I was hoping someone would make an addon for this. You did it a lot faster than I expected it would be done. Thanks again.

This review is for a previous version of the add-on ( 

As I stated in the Description, there are design issues. I have no plans to inject design rules, as they are likely to break the design completely in not supported versions of the theme changes. You might try to contact the developer of your favorite theme to add support for this extension and / or play around with userchrome css.
For information about userchrome: