title: How to add 'postcss config' to laravel mix?
body: <p>No matter how hard I try, but the plugins never seem to catch on.</p>
  
  <p>I tried to add the method .postCss - nothing</p>
  
  <p>I tried to give the path to the config also did not help</p>
  
  <pre><code>mix.sourceMaps('source-map').react('resources/assets/js/app.js', 'public/js')
    .webpackConfig({
      module: {
        rules: [
          {
            test: /\.css$/,
            loaders: [
                { loader: 'style-loader' },
                { loader: 'css-loader', options: { modules: true, importLoaders: 1, localIdentName: '[folder]_[name]__[local]--[hash:base64:5]' } },
                { loader: 'postcss-loader', 
                  options: {  plugins: () =&gt; {
                  postcssPresetEnv({
                    stage: 3,
                    features: {
                        'browsers': browsers,
                        'nesting-rules': true,
                    }
                  })
              }
            }
          }
        ]}
       ],
    }
  })
  </code></pre>