diff --git a/src/iframeResizer.contentWindow.js b/src/iframeResizer.contentWindow.js
index c77643f07..f0c7c6ad0 100644
--- a/src/iframeResizer.contentWindow.js
+++ b/src/iframeResizer.contentWindow.js
@@ -645,7 +645,7 @@
 
 	// document.documentElement.offsetHeight is not reliable, so
 	// we have to jump through hoops to get a better value.
-	function getComputedBodyStyle(prop) {
+	function getComputedStyle(prop,el) {
 		/* istanbul ignore next */  //Not testable in PhantomJS
 		function convertUnitsToPxForIE8(value) {
 			var PIXEL = /^\d+(px)?$/i;
@@ -667,9 +667,8 @@
 			return value;
 		}
 
-		var
-			el = document.body,
-			retVal = 0;
+		var retVal = 0;
+		el =  el || document.body;
 
 		/* istanbul ignore else */ // Not testable in phantonJS
 		if (('defaultView' in document) && ('getComputedStyle' in document.defaultView)) {
@@ -699,7 +698,7 @@
 			timer          = getNow();
 
 		for (var i = 0; i < elementsLength; i++) {
-			elVal = elements[i].getBoundingClientRect()[side] + getComputedBodyStyle('margin'+Side);
+			elVal = elements[i].getBoundingClientRect()[side] + getComputedStyle('margin'+Side,elements[i]);
 			if (elVal > maxVal) {
 				maxVal = elVal;
 			}
@@ -742,7 +741,7 @@
 	var
 		getHeight = {
 			bodyOffset: function getBodyOffsetHeight(){
-				return  document.body.offsetHeight + getComputedBodyStyle('marginTop') + getComputedBodyStyle('marginBottom');
+				return  document.body.offsetHeight + getComputedStyle('marginTop') + getComputedStyle('marginBottom');
 			},
 
 			offset: function(){