change articles width in hueman blog

Hallo

I would like to set a fixed width for articles, to avoid them being too wide and therefore difficult to read.
Important: keeping unchanged head width.
(For example, take a look here https://www.editorialedomani.it/politica/italia/con-il-tramonto-di-conte-vacilla-il-suo-sistema-di-potere-ethmdmxc)

Hueman only makes me choose how and whether to arrange the main body and sidebar, but not the width.

Many many thanks!!!

The page I need help with: [log in to see the link]