protected function checkHTML5()
    {
        if (in_array($this->_browser_name, ['Opera', 'Internet Explorer', 'Firefox', 'Iceweasel', 'Safari', 'Chrome', 'iPhone', 'iPod'])) {
            switch ($this->_browser_name) {
                case 'Opera':
                    if ($this->_version >= 10)
                        $this->_is_html5 = true;
                    break;
                case 'Internet Explorer':
                    if ($this->_version >= 9)
                        $this->_is_html5 = true;
                    if ($this->_chrome_frame === true && $this->_chrome_frame_version >= 6)
                        $this->_is_html5 = true;
                    break;
                case 'Firefox':
                case 'Iceweasel':
                    if ($this->_version >= 4)
                        $this->_is_html5 = true;
                    break;
                case 'Safari':
                    if ($this->_version >= 5)
                        $this->_is_html5 = true;
                    break;
                case 'Chrome':
                    if ($this->_version >= 9)
                        $this->_is_html5 = true;
                    break;
                case 'iPhone':
                case 'iPod':
                    $this->_is_html5 = true;
                    break;
            }
        }
    }