<rules
    xmlns="http://namespaces.plone.org/diazo"
    xmlns:css="http://namespaces.plone.org/diazo/css"
    >

    <rules css:if-content="body.theme1">
        <theme href="theme1.html"/>
    </rules>
    <rules css:if-content="body.theme2">
        <theme href="theme2.html"/>
    </rules>
    <copy css:theme="#content" css:content="body > *"/>
</rules>
