diff --git a/src/ol/control/zoomslidercontrol.js b/src/ol/control/zoomslidercontrol.js
index 6ee6224a40..f5d720bf27 100644
--- a/src/ol/control/zoomslidercontrol.js
+++ b/src/ol/control/zoomslidercontrol.js
@@ -189,20 +189,13 @@ ol.control.ZoomSlider.prototype.initSlider_ = function() {
   };
 
   var thumb = container.firstElementChild;
-  var thumbComputedStyles = window.getComputedStyle(thumb);
-  var thumbMargins = {
-    left: parseFloat(thumbComputedStyles['marginLeft']),
-    right: parseFloat(thumbComputedStyles['marginRight']),
-    top: parseFloat(thumbComputedStyles['marginTop']),
-    bottom: parseFloat(thumbComputedStyles['marginBottom'])
-  };
-  var thumbBorderBoxSize = {
-    width:thumb.offsetWidth, height: thumb.offsetHeight
-  };
-  var thumbWidth = thumbBorderBoxSize.width +
-      thumbMargins.right + thumbMargins.left;
-  var thumbHeight = thumbBorderBoxSize.height +
-      thumbMargins.top + thumbMargins.bottom;
+  var computedStyle = ol.global.getComputedStyle(thumb);
+  var thumbWidth = thumb.offsetWidth +
+      parseFloat(computedStyle['marginRight']) +
+      parseFloat(computedStyle['marginLeft']);
+  var thumbHeight = thumb.offsetHeight +
+      parseFloat(computedStyle['marginTop']) +
+      parseFloat(computedStyle['marginBottom']);
   this.thumbSize_ = [thumbWidth, thumbHeight];
 
   if (containerSize.width > containerSize.height) {
diff --git a/src/ol/map.js b/src/ol/map.js
index 9ebbc9ad81..fe35935ee1 100644
--- a/src/ol/map.js
+++ b/src/ol/map.js
@@ -1425,31 +1425,19 @@ ol.Map.prototype.updateSize = function() {
   if (!targetElement) {
     this.setSize(undefined);
   } else {
-    var targetElementComputedStyle = window.getComputedStyle(targetElement);
-    var borderBoxSize = {
-      width: targetElement.offsetWidth, height: targetElement.offsetHeight
-    };
-    var paddingBox = {
-      left: parseFloat(targetElementComputedStyle['paddingLeft']),
-      right: parseFloat(targetElementComputedStyle['paddingRight']),
-      top: parseFloat(targetElementComputedStyle['paddingTop']),
-      bottom: parseFloat(targetElementComputedStyle['paddingBottom'])
-    };
-    var borderBox = {
-      left: parseFloat(targetElementComputedStyle['borderLeftWidth']),
-      right: parseFloat(targetElementComputedStyle['borderRightWidth']),
-      top: parseFloat(targetElementComputedStyle['borderTopWidth']),
-      bottom: parseFloat(targetElementComputedStyle['borderBottomWidth'])
-    };
-    var size = {
-      width: borderBoxSize.width -
-      borderBox.left - paddingBox.left -
-      paddingBox.right - borderBox.right,
-      height: borderBoxSize.height -
-      borderBox.top - paddingBox.top -
-      paddingBox.bottom - borderBox.bottom
-    };
-    this.setSize([size.width, size.height]);
+    var computedStyle = ol.global.getComputedStyle(targetElement);
+    this.setSize([
+      targetElement.offsetWidth -
+          parseFloat(computedStyle['borderLeftWidth']) -
+          parseFloat(computedStyle['paddingLeft']) -
+          parseFloat(computedStyle['paddingRight']) -
+          parseFloat(computedStyle['borderRightWidth']),
+      targetElement.offsetHeight -
+          parseFloat(computedStyle['borderTopWidth']) -
+          parseFloat(computedStyle['paddingTop']) -
+          parseFloat(computedStyle['paddingBottom']) -
+          parseFloat(computedStyle['borderBottomWidth'])
+    ]);
   }
 };