public function renderVariable($val, $caller)
    {
        $output = '<pre style="background-color:#ccc;padding:5px;font-size:14px;line-height:18px;">';
        $output .= "<span style=\"font-size: 12px;color:#666;\">" . $this->formatCaller($caller) . " - </span>\n";
        if (is_string($val)) {
            $output .= wordwrap($val, self::config()->columns);
        } else {
            $output .= var_export($val, true);
        }
        $output .= '</pre>';

        return $output;
    }