What frameworks/libraries to use for the mobile version?

Question

HTML

I create a separate mobile version of the site. I thought to do it using boostrap and regular jQuery, but maybe there are some ready-made technologies that will greatly simplify development.
Share your knowledge with colleagues
Here are examples of layouts that I will stretch

Answer 1

which will greatly simplify the development

Unless - magic beans
In some cases, you can use a separate class to determine the device and load a separate template - mobiledetect.net