As you may already know, these are error pages. The code 404 corresponds to the "Not found" page, and the 403 error is "Forbidden".

If you have a domain name you can customize these pages. To do this go to the Menu > Administration > Favorites. It’s possible to choose a background color and the text to be displayed.

Warning! These are not the real pages, so no images, no links and no video are possible. These pages are not aimed at making referencing, but at showing to robots or users that there is an error.

The size of these two pages is strictly limited to several lines of text, some CSS and a link to go back to your home page.