Very easy to use, as long as you have node.js installed
In command line, install with:
npm i -g purgecss
then navigate to your export directory. Create a new folder called ‘purged’ (or anything you like)
then run the command below:
purgecss --css *.css **/*.css --content *.html *.js --output purged
The rewritten css files will then be stored in the ‘purged’ folder make sure you have the folder name after output
The *.js is to check to see if you have any styles dynamically generated in javascript so you could leave that out.
It should take bootstrap.min.css down to average 20kb, down from 159kb, depending on how much bootstrap you actually use.