public function appendStyles($scriptKey, $styles, $isFile = true)
    {
        // if has the script key already, ignore
        if (isset($this->_extraStyles[$scriptKey])) {
            return;
        }
        // add the styles
        $css = Openbizx::$app->getCssUrl();
        if ($isFile) {
            $_styles = "<link rel=\"stylesheet\" href=\"$css/" . $styles . "\" type=\"text/css\">";
            $this->_extraStyles[$scriptKey] = $_styles;
        } else {
            $this->_extraStyles[$scriptKey] = $styles;
        }
    }