Finally I managed to get rid of the old Drupal platform that I used for this site. I found the time to migrate the Drupal's database and to rewrite the old style.
On the other hand, over the last 15 years I've been carrying on the development of a CMS of mine (based on php/mariadb), which was not originally used for this site because of the lack of the time needed to build a new theme.
Now this site lives in a code that I have written by myself at 99%, even though tons of free classes and jQuery plug-ins are still embedded. This makes future upgrades much simpler and especially less time consuming than the nightmare Drupal's upgrades. In addition we now have a Mobile Responsive theme.
The part of the code concerning the "comments" was not fully tested and I would be glad if you guys will give me some feedback, so don't hesitate to drop me a note on the purpose.
Have fun!