I installed the free template J51 classic and: j51gridgallery, j51slideshow, j51thumbsgallery
and so far the template has always functioned properly.

Now I use DV SSL certificate provided free by my hosting for my site
and once activated the site was no longer visible.

Contacted the hosting, I was advised to add to the joomla index.php file the following statement:

$ _SERVER ['HTTPS'] = 'on';

In doing so the frontend of the site is visible but the formatting of menus, modules and etc is all busted.

What are the parts to be modified to correctly display https in the template and its modules?

Someone already had the same problem?

How did you solve it?

Thanks in advance and best wishes for the New Year.