Hello Florian. Thanks for this tuto, but it is not woeking for me. I am using Webpack 4. I did all your changes, but when i execute 'npm webpack' i recieve an error:

"ERROR in .[...filepath...]
Module build failed (from ./node_modules/postcss-loader/lib/index.js):
TypeError: Cannot read property 'type' of undefined"

Do you know what can be wrong here? Thanks!