title: z-index behaviour is different in chrome to firefox
body: <p>I have a bunch of CSS that is applied to a parent element and its children:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>.parent {
    position: fixed;
    top: 0px;
  }
  .el {
    position: fixed;
    top: 5px;
    z-index: 100;
  }
  .bodycontent {
    z-index: 1;
    position: relative;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div class="parent"&gt;
    &lt;div class="el"&gt;
      &lt;button&gt;&lt;/button&gt;
    &lt;/div&gt;
  &lt;/div&gt;
  &lt;div class="bodycontent"&gt;&lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>The page is made so that when it is scrolled, <code>.parent</code> goes underneath <code>.bodycontent</code> but <code>.el</code> goes above it. This works how I want it to in Firefox but not on Chrome.</p>
  
  <p>Any suggestions? I have tried messing around with different <code>z-index</code> values and different <code>position</code> values with no success.</p>