PurgeCSS (see WebVert, rapport d'intervention) when you modify css rules:

• work on css/style.css
• minify it on css/style-mini.css (Jekyll doesn't do it!)
• run PurgeCSS : -> npm update -> ./node_modules/.bin/purgecss -c purgecss.config.js -o css/purged (don't forget to change the head stylesheets link)