Postcss webpack simple

package.json

{
  "name": "Start it",
  "version": "1.0.0",
  "description": "project starter for static scaffolding",
  "main": "dist/js/bundle.js",
  "scripts": {
    "start": "webpack --watch",
    "build": "webpack",
    "build:prod": "webpack -p --config webpack.config.prod.js",
    "watch": "webpack --progress --watch",
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "Khangeldy Ilebaev <hongeldon@inbox.ru>",
  "license": "ISC",
  "devDependencies": {
    "babel-core": "^6.24.1",
    "babel-loader": "^7.0.0",
    "babel-preset-env": "^1.4.0",
    "browser-sync": "^2.18.8",
    "browser-sync-webpack-plugin": "^1.1.4",
    "copy-webpack-plugin": "^4.0.1",
    "css-loader": "^0.28.0",
    "css-mqpacker": "^6.0.1",
    "ejs": "^2.5.6",
    "ejs-render-loader": "^1.0.0",
    "extract-text-webpack-plugin": "^2.1.0",
    "file-loader": "^0.11.1",
    "html-webpack-plugin": "^2.29.0",
    "imagemin-webpack-plugin": "^1.4.4",
    "postcss-cssnext": "^2.10.0",
    "postcss-import": "^9.1.0",
    "postcss-loader": "^1.3.3",
    "style-loader": "^0.16.1",
    "stylelint-config-standard": "^16.0.0",
    "uglifyjs-webpack-plugin": "^0.4.3",
    "url-loader": "^0.5.8",
    "webpack": "^2.4.1"
  },
  "dependencies": {
    "gsap": "^1.19.1",
    "jquery": "^3.2.1"
  }
}

post-css-webpack.js

var webpack = require('webpack');
var path = require('path');
var BrowserSyncPlugin = require('browser-sync-webpack-plugin');
var ExtractTextPlugin = require('extract-text-webpack-plugin');
var HtmlWebpackPlugin = require('html-webpack-plugin');

module.exports = {
  entry: ['./src/App.js'],
  output: {
    filename: 'bundle.js',
    path: path.resolve(__dirname, 'dist/assets'),
    publicPath: './assets/'
  },
  devtool: 'inline-source-map',
  module: {
    rules: [
      {
        test: /\.jsx$|\.js$/,
        exclude: /node_modules/,
        loader: 'babel-loader',
        options: {}
      },
      {
        test: /\.css$/,
        use: ExtractTextPlugin.extract({
          fallback: 'style-loader',
          use: [
            {
              loader: 'css-loader',
              options: {
                importLoaders: 1,
                sourceMap: true
              }
            },
            'postcss-loader'
          ],
          publicPath: './'
        })
      },
      {
        test: /\.(jpg|png|gif)$/,
        use: 'file-loader'
      },
      {
        test: /\.(woff|woff2|eot|ttf|svg)$/,
        use: {
          loader: 'url-loader',
          options: {
            limit: 100000
          }
        }
      },
      {
        test: /\.ejs$/,
        exclude: /node_modules/,
        loader: 'ejs-render-loader'
      }
    ]
  },
  plugins: [
    new ExtractTextPlugin('style.css'),
    new HtmlWebpackPlugin({
      filename: '../index.html',
      template: 'src/ejs/index.ejs'
    }),
    // new webpack.optimize.UglifyJsPlugin({}),
    new BrowserSyncPlugin({
      host: 'localhost',
      port: 3000,
      server: {baseDir: ['dist']}
    })
  ]
}

postcss.config.js

module.exports = {
  plugins: [
    require('postcss-import'),
    require('postcss-cssnext')({ /* ...options */ }),
    require('css-mqpacker')
  ]
}