// function for changing stylesheets using
      // document.getElementsByTagName("link")
      function setLinkedStyleSheet(title) {
        var linkNodes = document.getElementsByTagName("link");
        for ( i = 0; i < linkNodes.length; i++ ) {
          linkNode = linkNodes[i];
          relAttr = linkNode.getAttribute('rel');
          if ( relAttr && ( relAttr.indexOf("style") != -1 ) && linkNode.getAttribute("title") ) {
            linkNode.disabled = true;
            if ( linkNode.getAttribute("title") == title )
              linkNode.disabled = false;
          }
        }
      }

      // function for changing stylesheets using document.styleSheets
      function setStyleSheet(theme) {
        for ( i = 0; i < document.styleSheets.length; i++ ) {
          if ( document.styleSheets[i].title ) {
            document.styleSheets[i].disabled = true;
            if ( document.styleSheets[i].title == theme )
              document.styleSheets[i].disabled = false;
          }
        }
      }