title: CSS glyphicon position bottom not working
body: <p>I have a simple question that I can't seem to figure out the answer to.  Why is bottom doing nothing in my example.  The parent position is set to relative, the child is absolute, the parent also has a height.  I can't seem to figure it out.  I know I can just use top, but I was curious as to why bottom doesn't work here.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>.profile-image-container {
    position: relative;
    height: 200px;
    width: 200px;
    background-color: yellow;
  }
  
  .profile-image-container .glyphicon {
    position: absolute;
    bottom: 50px;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;link href="http://netdna.bootstrapcdn.com/bootstrap/3.0.0/css/bootstrap.min.css" rel="stylesheet"/&gt;
  &lt;div class="profile-image-container"&gt;
    &lt;i class="glyphicon glyphicon-pencil"&gt;&lt;/i&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>