Adaptheme — theme-color -based dynamic toolbar v2.0
Adaptheme is a UI design tool to help designers visualize a web site with with a matching browser toolbar color that adapts to the site page. It takes the color from the "theme-color" attribute, for HTML pages offering that tag, otherwise it uses the color of the first row of pixels in the HTML page.
The add-on makes the browser toolbar theme adapting to the page content that the user is currently visiting. If you go to Facebook, you will get a Facebook-blue top toolbar.