diff --git a/slimbox2.js b/slimbox2.js
index e3d51ba..85f7a66 100644
--- a/slimbox2.js
+++ b/slimbox2.js
@@ -20,7 +20,7 @@ window.removeListener = (function() {
 addListener(window, 'load', function() {
 
 	// Global variables, accessible to Slimbox only
-	var options, images, activeImage = -1, activeURL, prevImage, nextImage, compatibleOverlay, middle, centerWidth, centerHeight,
+	var options, images, activeImage = -1, activeURL, prevImage, nextImage, noFixed, middle, centerWidth, centerHeight,
 		ie6 = !window.XMLHttpRequest, hiddenElements = [], els = {}, css, keyActions,
 		// Preload images
 		preload = {}, preloadPrev = new Image(), preloadNext = new Image();
@@ -59,6 +59,9 @@ addListener(window, 'load', function() {
 			f(i, a[i]);
 		}
 	}
+	function curStyle(e) {
+		return window.getComputedStyle ? getComputedStyle(e) : e.currentStyle;
+	}
 
 	// API
 
@@ -107,7 +110,8 @@ addListener(window, 'load', function() {
 			startImage = 0;
 		}
 
-		middle = document.documentElement.scrollTop + ((window.innerHeight || document.documentElement.offsetHeight) / 2);
+		middle = (document.documentElement.scrollTop || document.body.scrollTop) +
+			((window.innerHeight || document.documentElement.offsetHeight) / 2);
 		centerWidth = options.initialWidth;
 		centerHeight = options.initialHeight;
 		apply(els.center.style, {
@@ -117,8 +121,9 @@ addListener(window, 'load', function() {
 			marginLeft: (-centerWidth/2)+'px',
 			display: ''
 		});
-		compatibleOverlay = ie6 || (els.overlay.style && (els.overlay.style.position != "fixed"));
-		if (compatibleOverlay) els.overlay.style.position = "absolute";
+		var cs = curStyle(els.overlay);
+		noFixed = ie6 || cs && cs.position != "fixed";
+		if (noFixed) els.overlay.style.position = "absolute";
 
 		els.overlay.style.display = '';
 		setTimeout(function() {
@@ -153,10 +158,10 @@ addListener(window, 'load', function() {
 	function position() {
 		var l = document.documentElement.scrollLeft, w = document.documentElement.offsetWidth;
 		els.center.style.left = els.bottomContainer.style.left = (l + (w / 2))+'px';
-		if (compatibleOverlay) {
+		if (noFixed) {
 			apply(els.overlay.style, {
 				left: l+'px',
-				top: document.documentElement.scrollTop+'px',
+				top: '0px',
 				width: w+'px',
 				height: document.documentElement.offsetHeight+'px'
 			});