Thanks SilentBob.

I've certainly seen claims by people that they have made 100% pure CSS skins. There is a skin for sale called "LastSupper" that is supposed to be pure css.

Exactly...  ok, gang. I think we have another convert from CSS purist to tables in moderation. 

BTW, you can also keep the divs for the skin panes (the runat="server" elements) and just wrap them with a table cell that has your ID . 
This way you will have a known client-side ID to use with ID selectors. Otherwise the ASP.Net framework makes the client-side ID almost unable to be used.

A simple example would look like this:

<table cellpadding="0" cellspacing="0" style="border:none;">
<tr>
<td id="leftpane"><div id="leftpane" runat="server" /></td>
<td id="contentpane"><div id="contentpane" runat="server" /></td>
<td id="rightpane"><div id="rightpane" runat="server" /></td>
</tr>
</table>

That way you can target the contentpane with CSS like this:

#contentpane {
   background-color:#f1f1f1;

}

It also allows you to put images inside the table cell without getting a server error.