title: Autoprefixer errors with NPM (✖ Plugin Error: Cannot find module )
body: <p>So currently I am having troubles with autoprefixer.</p>
  
  <p>I have downloaded postcss-cli and autoprefixer to --save-dev and -g</p>
  
  <p>When I run a command like this:</p>
  
  <pre><code>postcss ../../../htdocs/css/workflow/homepage-announcements.css -o ../../../htdocs/css/workflow/homepage-announcements.css
  </code></pre>
  
  <p>works fine with an output of:</p>
  
  <blockquote>
    <p>✔ Finished ../../../htdocs/css/workflow/homepage-announcements.css (25ms)</p>
  </blockquote>
  
  <p>Now that I have used <code>--use autoprefixer</code> an error is thrown. Command below.</p>
  
  <pre><code>postcss --use autoprefixer ../../../htdocs/css/workflow/homepage-announcements.css -o ../../../htdocs/css/workflow/homepage-announcements.css
  </code></pre>
  
  <p>Error message:</p>
  
  <blockquote>
    <p>✖ Plugin Error: Cannot find module '../../../htdocs/css/workflow/homepage-announcements.css'</p>
  </blockquote>
  
  <p>I Have tried everything and still have no solution :(</p>
  
  <pre><code>{
      "name": "homepage-announcements",
      "version": "2.0.0",
      "description": "Homepage announcements",
      "main": "js/Default.js",
      "dependencies": {
         "react": "^15.4.2"
       },
      "devDependencies": {
      "autoprefixer": "^6.7.7",
      "ava": "^0.18.2",
      "babel-loader": "^6.4.1",
      "eslint": "^3.19.0",
      "node-sass": "^4.5.2",
      "postcss": "^5.2.16",
      "postcss-cli": "^3.1.1",
      "webpack": "^2.3.3",
      "xo": "^0.18.1"
      },
      "scripts": {
  
      "build": "webpack -p &amp;&amp; npm run sass &amp;&amp; npm run css",
      "sass": "node-sass scss/default.scss ../../../htdocs/css/workflow/homepage-announcements.css --output-style compressed &amp;&amp; npm run css",
      "css": "postcss --use autoprefixer ../../../htdocs/css/workflow/homepage-announcements.css -o ../../../htdocs/css/workflow/homepage-announcements.css",
      "lint": "xo js/*.js js/**/*.js js/**/**/*.js js/**/**/**/*.js js/**/**/**/**/*.js js/**/**/**/**/**/*.js"
  }
  </code></pre>