// function for changing stylesheets using
      // 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;
          }
        }
      }