title: Iframe dosent work
body: <p>I have code:</p>
  
  <pre><code>&lt;iframe src="in1.html" width="400" height="300" id="f1"&gt;
  &lt;p&gt;Your browser does not support iframes.&lt;/p&gt;
  &lt;/iframe&gt;
  
  &lt;script&gt;
  var childFrame = document.getElementById("f1").contentWindow;
  childFrame.document.body.style.backgroundColor = "yellow"
  &lt;/script&gt;
  </code></pre>
  
  <p>When i load page yellow is show on but then white background is load. Why?</p>