webpack.config.js

const HtmlWebpackPlugin = require('html-webpack-plugin');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');

module.exports = {
  entry: './app/app.js',
  target: 'electron-renderer',
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: {
          loader: 'babel-loader'
        }
      },
      {
        test: /\.html$/,
        use: {
          loader: 'html-loader'
        }
      },
      {
        test: /\.css$/,
        use: [
          {
            loader: MiniCssExtractPlugin.loader
          },
          {
            loader: 'css-loader',
            options: {
              modules: {
                localIdentName: '[hash:base64:5]'
              },
              importLoaders: 1
            }
          }
        ],
      },
      {
        test: /\.png$/,
        use: {
          loader: 'url-loader?mimetype=image/png'
        }
      }
    ]
  },
  plugins: [
    new HtmlWebpackPlugin({
      template: './app/index.html',
      hash: true
    }),
    new MiniCssExtractPlugin({
      filename: '[name].css',
      chunkFilename: '[id].css'
    })
  ]
};