@Nirzar ran cd core/docs/kss; make to build the mediawiki.ui desktop style guide.

npm installed the latest kss version 2.0.2 per package.json, but then the kss-node command failed with

{{whenDepth expression}} is deprecated; use {{ifDepth expression}} instead.

core/docs/kss/styleguide-template/index.html uses {{whenDepth}}. He fixed that and got another deprecation error.

It builds fine for me, npm list kss says I'm running kss@0.3.7.

According to https://github.com/kss-node/kss-node/releases these features were deprecated in version 2, so I think changing package.json to

"kss": ">=0.3.7 <=1.2.0"

would fix this. Or someone could update core/docs/kss/styleguide-template/index.html , but they would probably have to bump up the required version in package.json.