Technical Documentation Page Project Feedback Needed

After quite a bit of time and redoing the navigation bar 3 times, I think I did it.
I took the freeCodeCamp’s article on HTML for beginners and did it all over again with a new design for mobiles, tablets and large displays.

Any feedback is welcome. Thanks in advance.

You can see the website at: mydesign1373.atwebpages.com

Here are the HTML and CSS codes : GitHub - PhilipMHF/HTML-for-Beginners: This is a freeCodeCamp project