Ajax CalendarExtender displaying at wrong position in Chrome

<script type="text/javascript" language="javascript">

    function onCalendarShown(sender, args) {

        // Get Image that was clicked to open calendar

        var calendarImage = $get('<%=txtDate.ClientID %>');

        // Set new calendar position

        sender._popupDiv.parentElement.style.top = calendarImage.offsetTop + calendarImage.height + 'px';

        sender._popupDiv.parentElement.style.left = calendarImage.offsetLeft + 'px';

    }

  

    </script>

 ...............................................................................

    <asp:TextBox ID="txtDate CssClass="textboxstyledatetime" runat="server"></asp:TextBox>

<ajaxToolkit:CalendarExtender ID="CalendarExtender1" Format="dd/MM/yyyy" runat="server"

PopupButtonID="ibtnCalendar" TargetControlID="txtDate" OnClientShown="onCalendarShown"> </ajaxToolkit:CalendarExtender>