diff --git a/examples/xhtml.html b/examples/xhtml.html
index d209aeba9f..e93239bebb 100644
--- a/examples/xhtml.html
+++ b/examples/xhtml.html
@@ -1,10 +1,10 @@
 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
         "http://www.w3.org/TR/2000/REC-xhtml1-20000126/DTD/xhtml1-strict.dtd">
-        <html xmlns="http://www.w3.org/1999/xhtml">
-        <head>
+<html xmlns="http://www.w3.org/1999/xhtml" style="width:100%">
+<head>
 <script src="../lib/OpenLayers.js"></script>
 </head>
-<body>
+<body style="width:100%">
   <div style="width:100%; height:500px" id="map"></div>
   <script defer="defer" type="text/javascript">
     var map = new OpenLayers.Map('map');
diff --git a/lib/OpenLayers/Map.js b/lib/OpenLayers/Map.js
index 8b9265350f..0213e19fdb 100644
--- a/lib/OpenLayers/Map.js
+++ b/lib/OpenLayers/Map.js
@@ -468,10 +468,22 @@ OpenLayers.Map.prototype = {
     */
     updateSize: function() {
         var newSize = this.getCurrentSize();
-        
-        if (!newSize.equals(this.getSize())) {
-            this.events.element.offsets = null;
+        var oldSize = this.getSize();
+        if (oldSize == null)
+            this.size = oldSize = newSize;
+        if (!newSize.equals(oldSize)) {
+            // move the layer container so that the map is still centered
+            var dx = (newSize.w - oldSize.w) / 2,
+                dy = (newSize.h - oldSize.h) / 2;
+            var lcStyle = this.layerContainerDiv.style;
+            lcStyle.left = (parseInt(lcStyle.left) + dx) + "px";
+            lcStyle.top  = (parseInt(lcStyle.top ) + dy) + "px";
+            // reset the map center
+            this.layerContainerOrigin = this.center.clone();
+            // store the new size
             this.size = newSize;
+            // the div might have moved on the page, also
+            this.events.element.offsets = null;
         }
     },
     
