Thanks for the precious help, I was really lost. The site is now fully functional and complete.
A detail, on the homepage the modules in the positions: "header_bottom" "top1" "top2" "Bottom 6" were arranged in side-by-side columns for the same type of position. (as you can see on the homepage of the main domain site, which is published online).
Even on the pages of the various articles, at the bottom the modules in the "Bottom 6" position are no longer arranged in side-by-side columns.
They are now in horizontal bars, no longer arranged in columns.
I don't know if I was right to request clarification on the module positions in this post or if I should have opened another post.
Thanks in advance for any guidance.