title: Override Ionic Header with custom color
body: <p>Is it possible to customize the color of a header with ionic ? 
  By custom, I mean using a custom color and not one of the <code>bar-something</code> that are defined. 
  I've tried this, but it doesn't seem to work</p>
  
  <pre><code>&lt;ion-nav-bar class="bar-positive custom-dark"&gt;
  &lt;/ion-nav-bar&gt;
  </code></pre>
  
  <p>and in CSS: </p>
  
  <pre><code> .custom-dark{
   color : #30393A;
   }
  </code></pre>
  
  <p><a href="http://codepen.io/NinaLysa/pen/JdjzjM" rel="nofollow">Here is a codePen </a> </p>
  
  <p>I don't seem to be able to change the blue color. </p>