How to make a website, display his content on all devices?

Question

I've completed a nice website. I've already buy a hosting plan an domain name just for it. But, i don't know why, my website is an interresting thing only on my computer; On smartphone, it's a not good to see at all. I want to fix it the problem

Answer 1

Use responsive design!

Answer 2

Try going through css grid tutorial or responsive website tutorial.

That can solve the problem.
Or if you want a shortcut try searching for w3.css