CSS Grid is the easiest, cleanest and powerful way to deal with responsiveness, a completely new approach baked in the last years and ready to use.

CSS Grid changes how you used to layout your documents, instead of divitis (plenty of divs) and JavaScript to change div positions depending on screens (what Bootstrap does nowadays), you can use pure CSS grid layouts with just the meaningful divs and independently of document source order.

You don’t need to touch HTML or JavaScript, you don’t need Bootstrap, forget about flexbox in CSS or even complex CSS rules, what you see in your CSS is what you get on your screen.

Play stretching your browser to check the JSFiddle result.

I would recommend you to do these examples: https://gridbyexample.com/examples/

Fall in love with templates like I did ❤