CSS Web Performance
In this repo you will find a Gulpfile by means of which you will be able to minify your CSS file and also remove unused CSS selectors. This will make your CSS file extremely small and thus improve your website performance. Feel free to adjust it to your needs. In my case, in a small project, I went from a 44ko file to a 7ko file, which is a considerable gain (more than 6x smaller).
You can download the dependencies with :
npm install gulp gulp-sass gulp-sourcemaps gulp-postcss postcss-uncss uncss cssnano gulp-notify -D