@Media Query related problems in Technical Documentation Page

I have solved this challenge but I was having problems in making this page responsive and had to copy FCC code related to media query.
Still, this page has some problems which I am unable to fix.

Can you help understand two specific things?

(i) How can I make navigational section as grid with two or more column with auto-fill whenever it’s accessed on smaller screen

(ii) While transitioning to smaller screen, there are times where contents get hidden, how can I fix that?