Index: misc/autocomplete.js
===================================================================
--- misc/autocomplete.js	(revision 26)
+++ misc/autocomplete.js	(working copy)
@@ -170,6 +170,8 @@
  * Positions the suggestions popup and starts a search
  */
 Drupal.jsAC.prototype.populatePopup = function () {
+  var $input = $(this.input);
+  var position = $input.position();
   // Show popup
   if (this.popup) {
     $(this.popup).remove();
@@ -179,11 +181,12 @@
   this.popup.id = 'autocomplete';
   this.popup.owner = this;
   $(this.popup).css({
-    marginTop: this.input.offsetHeight +'px',
-    width: (this.input.offsetWidth - 4) +'px',
+    top: parseInt(position.top + this.input.offsetHeight, 10) + 'px',
+    left: parseInt(position.left, 10) + 'px',
+    width: $input.innerWidth() + 'px',
     display: 'none'
   });
-  $(this.input).before(this.popup);
+  $input.before(this.popup);
 
   // Do search
   this.db.owner = this;