public static function loadGoogleFontsJson()
 {
     if (self::$_fonts) {
         return self::$_fonts;
     }
     $fileName = 'googlefonts.json';
     $filePath = ZO2PATH_ROOT . DIRECTORY_SEPARATOR . $fileName;
     if (file_exists($filePath)) {
         $content = file_get_contents($filePath);
         self::$_fonts = json_decode($content, true);
         return self::$_fonts;
     } else {
         return null;
     }
 }