public function getCss()
    {
        switch ($this->type) {
            case self::TYPE_ERROR:
                $css = 'danger';
                break;
            case self::TYPE_WARNING:
                $css = 'warning';
                break;
            case self::TYPE_INFO:
                $css = 'info';
                break;
            case self::TYPE_SUCCESS:
                $css = 'success';
                break;
            default:
                $css = 'info';
                break;
        }

        return $css;
    }