$(document).ready(function () {
  	function pageY(elem) {
  		return elem.offsetParent ? (elem.offsetTop + pageY(elem.offsetParent)) : elem.offsetTop;
  	}
  
  	var buffer = 5; //scroll bar buffer
  	function resizeIframe() {
  		var height = document.documentElement.clientHeight;
  		height -= pageY(document.getElementById('ifm')) + buffer;
  		height = (height < 0) ? 0 : height;
  		document.getElementById('ifm').style.height = height + 'px';
  	}
  
  	document.getElementById('ifm').onload = resizeIframe;
  	window.onresize = resizeIframe;
  });