title: Change css when dropdown is not selected
body: <p>Can someone help me with this. Here is the plunker. </p>
  
  <p><a href="http://plnkr.co/edit/M3rJYnqhODRapXBBI6Ck?p=preview" rel="nofollow">http://plnkr.co/edit/M3rJYnqhODRapXBBI6Ck?p=preview</a></p>
  
  <p>As shown in the plunker, i have date, user, car, speed and mileage as input fields. </p>
  
  <p>I want the input values for mileage and speed to have text color as red initially. Only when i select dropdown value for user and car, the text color should then change to black. </p>
  
  <p>can someone suggest ?</p>
  
  <pre><code>&lt;html&gt;
  &lt;/html&gt;
  </code></pre>