webpack.config.js

var HtmlWebpackPlugin = require('html-webpack-plugin');
var HtmlWebpackPluginConfig = new HtmlWebpackPlugin({
  template: __dirname + '/app/index.html',
  filename: 'index.html',
  inject: 'body'
});
var ExtractTextPlugin = require('extract-text-webpack-plugin');
var webpack = require('webpack');

module.exports = {
  entry: [
    './app/index.js'
  ],
  output: {
    path: __dirname + '/dist',
    filename: 'bundle.js'
  },
  module: {
    loaders: [
      {test: /\.js$/, exclude: /node_modules/, loader: "babel-loader"},
      {test: /\.css$/, loader: ExtractTextPlugin.extract("style-loader","css-loader") }
    ]
  },
  plugins: [
    HtmlWebpackPluginConfig,
    new ExtractTextPlugin("bundle.css"),
    new webpack.DefinePlugin({
      'process.env': {
        'NODE_ENV': JSON.stringify(process.env.NODE_ENV)
      }
    })
  ]
}