title: Empty div (with style: height) will not display
body: <p><em>Incredibly</em> simple piece of HTML - but not displaying how I would expect. </p>
  
  <p>I'm trying to create an empty div that displays as whitespace on the top of the page, with <code>style="height: 400px;"</code></p>
  
  <p>Even though I have specified a height, my empty div will not display. What am I missing here? </p>
  
  <p><strong>UPDATE: my main question is:  Why does an empty div not display even if it has a height set? Or, what are the basic <code>style</code> rules needed to display an empty div?</strong></p>
  
  <p>Full code:</p>
  
  <pre><code>&lt;html&gt;
  &lt;head&gt;&lt;title&gt;Site Name&lt;/title&gt;
  &lt;/head&gt;
  &lt;body&gt;
  &lt;div style="height:400px; width:100%; margin:0; padding:0; position:absolute;"&gt;&lt;/div&gt;
  &lt;div style="width: 50%; margin: auto;"&gt;
  &lt;img src="logo.gif"&gt;&lt;/div&gt; 
  
  &lt;div style="width: 50%; margin: auto;"&gt;&lt;/div&gt;
  
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>