Non-uniform responsive layout

I'm working in a brazillian federal university site
https://cidhurb.uff.br/home
with DIVI builder in WordPress/WP Multi User
installation.
The DIVI uses a child theme created by IT
university team and the WP have restrictions
(althought I have admin user role) - plugins
and theme code editors are blocked.

I'My problem: I'm Reading about DIVI structure
(seems that the DIVI responsive CSS Style
sheets have heritage; desktop CSS is replicated
in tablet CSS and Tablet is cloned to mobile CSS;
CSS mobile from itself rewrites all the other CSS
rules - ?) but I cant set the mobile page without
horizontal page rolling.

My DIVI installation is legal, but I don't have access
to IT team to get purchase info to access DIVI
suport help.
The DIVI didn't offers page designs ready made
to start a page with all responsive settings done.

Who can help me?