How to change template on mobile devices?

Question

opencart

Hello forumites. In connection with the complete redesign of the mobile version of the site, the alteration of almost everything that is possible, an automatic transition from the main template to the mobile one is required. I found an option on the Internet using Mobile_Detect.php, but for some reason the site crashes on mobile devices



in the system/startup.php file add
require_once(DIR_SYSTEM . 'library/Mobile_Detect.php');
$detect = new Mobile_Detect();
define('isMobile', $detect->isMobile(), false);//We use this
define('isTablet', $detect->isTablet(), false); //We use this and add //Mobile

in the index file if(isMobile && !isTablet && $_COOKIE['ver'] !== 'full'){ $this->

}elseif(isMobile && !isTablet && $_COOKIE['ver'] == 'full'){
$this->config->set('config_template', 'default');
}

Maybe this construction does not work on version 3 of opencart?