title: Center position fixed horizontally
body: <p>I want to dynamically append to the end of the <code>body</code> a fixed-positioned to the bottom box that has 1000px width and is centered horizontally.</p>
  
  <p>When I create it with percentage width I can easily add margins and everything is ok, but when I have it in pixels I can't add margins anymore (it has to be responsive). <code>auto</code> doesn't work either.</p>
  
  <p>How can I do that?</p>
  
  <pre><code>&lt;div style="position: fixed; bottom: 0; width: 1000px; margin: 0 auto; padding: 0;height: 100px; background-color: green;"&gt;
  &lt;/div&gt;
  </code></pre>