FoxColorBox is a Firefox extension that allows you to change and customize browser Window colors. When you open a new window, it will have a distinct color. You can also change colors by clicking on the extension icon.

This can help you differentiate between home, work, and school. It can also be useful when working in development, staging and production environments.

https://addons.mozilla.org/en-US/firefox/addon/foxcolorbox/

https://github.com/jftuga/foxcolorbox