A website can be opened by the user in different screen size devices like computer, laptop, mobile etc .. The website's automatic adjustment of the screen size of the device is called responsive website design. It is necessary to make the website responsive in order to be able to use it easily.
1 can design a responsive web site with the help of bootstrap
It is easy to use 2 bootstrap which has basic knowledge of html and css, it can use it easily.
3 bootstrap supports almost all browsers.