Responsive web design is working on desktop but not on mobile device

Question

You are probably missing the viewport meta tag in the html head:

 <meta name="viewport" content="width=device-width, initial-scale=1">

Without it the device assumes and sets the viewport to full size.

More info here.

I have also faced this problem. Finally I got a solution. Use this bellow code. Hope: problem will be solve.

<meta name="viewport" content="initial-scale=1, maximum-scale=1">

Though it is answered above and it is right to use

<meta name="viewport" content="width=device-width, initial-scale=1">

but if you are using React and webpack then don't forget to close the element tag

<meta name="viewport" content="width=device-width, initial-scale=1" />