webpack.config.js

const path = require('path');
const ExtractTextPlugin = require('extract-text-webpack-plugin');

module.exports = {
  entry: './src/index.js',
  output: {
    filename: 'main.js',
    path: path.resolve(__dirname, 'dist')
  },
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        exclude: /node_modules/,
        use: { loader: `babel-loader` }
      },
      {
        test: /\.css$/,
        use: ExtractTextPlugin.extract({
          fallback: `style-loader`,
          use: `css-loader`
        })
      }
    ]
  },
  plugins: [
    new ExtractTextPlugin('main.css'),
  ]
};