function resize_iframe()
{
  //resize the iframe according to the size of the
  //window (all these should be on the same line)
  document.getElementById("cn_iframe").style.height=parseInt(document.body.clientHeight-document.getElementById("cn_iframe").offsetTop-200)+"px";
}

// this will resize the iframe every
// time you change the size of the window.
//window.onresize=resize_iframe;