postcss-sass | Use Sass as a PostCSS plugin | Style Language library

You can drop the wildcard from shx cp -R public/* ../server-project/public, as the recursive flag will pick up everything in the source directory. This should get you what you are after -

gatsby-plugin-postcss use specific postcss plugin(postcss-preset-env, for example) to handle css code, itself is not a postcss plugin, so you can't use it in postCssPlugins option.

And the pipeline for gastby to handle sass file is sass -> postcss plugin -> final result, so just use sass plugin and choose postcss in its option postCssPlugins.

It turned out the problem was with a missing semicolon in "app.scss". It worked fine when it was a plain css, and stopped working when I converted it to SASS.

Like I said in the question, the problem was the compiler was failing to compile the scss files of the components when they try to import an scss file from node_modules.

I resolved it with sass-loader applying the following rule for scss in the webpack.config.common.js:

Postcss-sass-color-functions is no longer maintained as mentioned in their repository.

You can use postcss-preset-env instead with color-mod-function enabled to do the same.

So now I got this error again, and wanted to confirm that the answer of Dan Cancro did the trick!

Here's exactly what I did (for others in order not to waste as much time as I did):

1. I changed "postcss-loader": "1.3.0" to "postcss-loader": "1.3.3"

2. Deleted /node_modules folder

3. removed package-lock.json file

4. ran npm install

5. ran yarn run webpack:build

That solved the issue for me.

Solved !!

I first tried to install Python via git, it didn't install or I did something wrong since I am a newbie at git environment, so I installed it via visual studio, and put the following into path environment variables :

So it turns out Gatsby is using Webpack 1 and I had somehow ended up with "extract-text-webpack-plugin": "^3.0.0" and that version is only compatible with Webpack 3.

After I tried yarn add extract-text-webpack-plugin@^1.0.1, npm run clean and npm run build, the styles.css is now filled with CSS and serve shows the website with styles.