Cleancss as a transform stream
npm install cleancss-transform> Cleancss transform stream
``
npm i -D cleancss-transform
`
import fs from 'fs'
import cleancss from 'cleancss-transform'
fs.createReadStream( 'styles.css' )
.pipe( cleancss() )
.pipe( fs.createWriteStream( 'main.css' ) )
``