Here's the source code to the extension: https://github.com/painty/CSS-Used-ChromeExt https://github.com/painty/CSS-Used-ChromeExt I created an experiment to d

Here's the source code to the extension: https://github.com/painty/CSS-Used-ChromeExt https://github.com/painty/CSS-Used-ChromeExt I created an experiment to do this 8 years ago (time sure does fly): https://github.com/driverdan/cssess https://github.com/driverdan/cssess There have been a bunch of other projects that do this as well. purifycss, purgecss, and uncss among others.