code: def head(self, request, website):
          
          stylesheet = self.stylesheetLocation
          if stylesheet is not None:
              root = website.rootURL(request)
              for segment in stylesheet:
                  root = root.child(segment)
              return tags.link(rel='stylesheet', type='text/css', href=root)
docs: Provide content to include in the head of the document.  If you only
          need to provide a stylesheet, see L{stylesheetLocation}.  Otherwise,
          override this.
  
          @type request: L{inevow.IRequest} provider
          @param request: The request object for which this is a response.
  
          @param website: The site-wide L{xmantissa.website.WebSite} instance.
              Primarily of interest for its C{rootURL} method.
  
          @return: Anything providing or adaptable to L{nevow.inevow.IRenderer},
              or C{None} to include nothing.