title: why can't you use iframe absolute positioning to set height/width
body: <p>My question is similar to <a href="https://stackoverflow.com/questions/3979000/iframe-and-conflicting-absolute-positions">IFRAME and conflicting absolute positions</a>, but I specifically want to know <strong>WHY</strong> you can't set both the left/right or top/bottom in an iframe and get it to work.</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;head&gt;
  &lt;style type="text/css"&gt;
  iframe { position: absolute; display: block; top: 0; bottom: 0; left: 10px; width:100px;   border: 1px solid black;}
  div { position: absolute; display: block; top: 0; bottom: 0; left: 200px; width:100px;  border: 1px solid black;}
  &lt;/style&gt;
  &lt;/head&gt;
  &lt;body&gt;
  &lt;iframe&gt;&lt;/iframe&gt;
  &lt;div&gt;&lt;/div&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>The div takes up the full browser height.  The iframe is 150px tall.  It's the same in Chrome 17, Firefox 11, and IE9.  Clearly this isn't a browser quirk.  There's something in the HTML5 spec that says you can't set both left/right or top/bottom on an iframe in order to set the height.  </p>
  
  <p>What is special about iframes (vs. divs)?</p>