title: How to add postcss-mixins on top of postcss-env-preset?
body: <p>I want to add postcss-mixins to my project running fine with postcss-env-preset, tried but mixins are not working, below is my postcss.config.js:</p>
  
  <pre><code>const path = require('path');
  const postcssPresetEnv = require('postcss-preset-env')
  const mqpacker = require('css-mqpacker')
  const postcssMixins = require('postcss-mixins')
  module.exports = {
      plugins:  [
          postcssMixins(),
          new postcssPresetEnv(
              {
                  stage: 0,
                  importFrom: path.resolve(__dirname, "./util/global.css")
              }
          ),
          mqpacker({
              sort: function (a, b) {
                  return a.localeCompare(b);
              }
          }),
  
      ]
  }
  </code></pre>
  
  <p>output css files simply let the @mixins line untouched:
  <a href="https://i.imgur.com/oYSoPEr.png" rel="nofollow noreferrer">https://i.imgur.com/oYSoPEr.png</a></p>