Hi,
You can use the following in your layout.master for the alt content panels:
<portal:LayoutPanel ID="divAlt1" runat="server" SkinID="TopPane">
<asp:ContentPlaceHolder ID="altContent1" runat="server"></asp:ContentPlaceHolder>
</portal:LayoutPanel>
<portal:LayoutPanel ID="divAltContent2" runat="server" SkinID="BottomPane">
<asp:ContentPlaceHolder ID="altContent2" runat="server"></asp:ContentPlaceHolder>
</portal:LayoutPanel>
And then add the following to your theme.skin file:
<portal:LayoutPanel runat="server" SkinID="TopPane"
Element="div"
ExtraCssClasses="top-pane clearfix"
/>
<portal:LayoutPanel runat="server" SkinID="BottomPane"
Element="div"
ExtraCssClasses="bottom-pane clearfix"
/>
Notice the SkinIDs on the LayoutPanel controls.
HTH,
Joe D.