This is not really a tutorial, it's more an overview of what responsive design is. Build a responsive website from start to finish without the use of bootstrap for a change. Just a plain css grid and start from there.

"You made it so clear, concise and made it to a point that I believe anybody who wants to create a
website can do the same. My hats off appreciations to your well thought out instructions and the effort you have put into it."

You have no idea how much a 71-year old deeply appreciates your help ...