Optimize production CSS to avoid the browser to download dead code

[clemlesne]

trafficstars

Describe the enhancement you want

Reduce unused rules from stylesheets and defer CSS not used to decrease bytes consumed by network activity.

PurgeCSS can be used for that. Next.js is supported out of the box.

[linear[bot]]

ENG-4764 Optimize production CSS to avoid the browser to download dead code