Hi Bert,
You're missing the Left, Center and Right Panels. Replace your asides and article sections with the following:
<aside id="left">
<asp:Panel id="divLeft" runat="server" cssclass="leftside col2" visible="True" SkinID="pnlPlain">
<asp:ContentPlaceHolder ID="leftContent" runat="server"></asp:ContentPlaceHolder>
</asp:Panel>
</aside>
<article>
<asp:Panel id="divCenter" runat="server" visible="true" cssclass="center-nomargins" SkinID="pnlPlain">
<portal:Breadcrumbs ID="Breadcrumbs" runat="server"></portal:Breadcrumbs>
<portal:ChildPageMenu ID="ChildPageMenu" runat="server" CssClass="txtnormal"></portal:ChildPageMenu>
<a id="startcontent"></a>
<asp:ContentPlaceHolder ID="mainContent" runat="server"></asp:ContentPlaceHolder>
</asp:Panel>
</article>
<aside id="right">
<asp:Panel id="divRight" runat="server" visible="true" cssclass="rightside col3" SkinID="pnlPlain">
<asp:ContentPlaceHolder ID="rightContent" runat="server"></asp:ContentPlaceHolder>
</asp:Panel>
</aside>
In addition:
-
You don't need the id and runat on the HTML element.
-
Considering your design is HTML5, your doctype should be <!DOCTYPE html> and you don't need the XMLNS on the HTML element.
HTH,
Joe D.