Example of how to load static CSS files from node_modules using webpack?

For users who have encountered a similar problem, there are steps that I’ve done to get it working, I’m not sure that this equilibrium way.

1. npm install file-loader --save
2. add import 'leaflet/dist/leaflet.css'; in main app.js
3. change webpack.config.js by following way:

add css-loader to get rid of SyntaxError: Unexpected token . and next add file-loader and match files to get rid of Uncaught Error: Cannot find module "./images/layers.png":

module.exports = {
  entry: "./web/static/js/app.js",
  output: {
    path: "./priv/static/js",
    filename: "app.js"
  },
  module: {
    loaders: [{
      test: /\.jsx?$/,
      exclude: /node_modules/,
      loader: 'babel'
    }, {
      test: /\.scss$/,
      loader: ExtractTextPlugin.extract(
        'style',
        'css' + '!sass?outputStyle=expanded&' + stylePathResolves
      )
    }, {
      test: /\.css$/,
      loader: "style-loader!css-loader"
    }, {
      test: /\.(png|jpg|jpeg|gif|svg|woff|woff2|ttf|eot)$/,
      loader: 'file-loader'
    }]
  },
  plugins: [new ExtractTextPlugin("app.css")]
};

At the beginning I got this config from some example and it’s not 100% clear why I’ve used ExtractTextPlugin to load scss and what the correlation is with css-loader, maybe to be more coherent should I use ExtractTextPlugin also in this part, maybe someone knows and can code review? But my solution is working and I can work further.