Missing NODE_PATH lets PostCSS fail because it cannot find global modules

[moritzheiber]

postcss, postcss-cli and autoprefixer are globally installed modules. Unfortunately, if the theme has a "local" postcss.config.js (e.g. like the docsy theme) npm fails to resolve the global module path and therefore thinks the autoprefixer module is missing.

Adding NODE_PATH to the execution run for a relevant GitHub Action fixes the problem (reference, example).

I would suggest adding echo `npm root -g` >> /etc/profile somewhere inside the Dockerfile for the primary container.