public static function navbar($content, $htmlOptions = array())
    {
        self::addCssClass('navbar', $htmlOptions);
        $display = TbArray::popValue('display', $htmlOptions);
        if (!empty($display)) {
            self::addCssClass('navbar-' . $display, $htmlOptions);
        }
        $color = TbArray::popValue('color', $htmlOptions, 'default');
        if (!empty($color)) {
            self::addCssClass('navbar-' . $color, $htmlOptions);
        }
        $htmlOptions['role'] = 'navigation';
        $output = self::openTag('nav', $htmlOptions);
        $output .= $content;
        $output .= '</nav>';
        return $output;
    }