title: CSS opacity change on div with time delay not user interaction
body: <p>I'm trying to set up an image within a div that will slowly appear (opacity from 0 to 1) over 5 seconds. I have this code:</p>
  
  <pre><code>.fadeDivIn {
  opacity: 1;
  transition: opacity 5s ease-in;
  -moz-transition: opacity 5s ease-in;
  -webkit-transition: opacity 5s ease-in;
  -o-transition: opacity 5s ease-in;
  }
  </code></pre>
  
  <p>but I can't figure out how to trigger it automatically.</p>
  
  <p>I've been doing transitions to other elements with CSS3 keyframes and would ideally like to apply something similar to opacity but have hit a brick wall. Can anyone help please?</p>