What i'm doing wrong?

Someone will say what is the problem here? How to make h1, h2, h3 responsive?

Hi there! My advice would be to make use of bootstrap classes such as container. You can read about it here: https://getbootstrap.com/docs/4.0/layout/overview/#containers. My guess is if you put your whole content in a “div” with class “container” your problem may be solved. But I don’t know for sure.

Try changing the left and right margins of your h1 CSS selector from a fixed 300px to a percentage such as 5%. That way, when the screen width gets smaller, the margins are not locked into a fixed position.

The same thing above applies to your h2 and h3 CSS selectors.