How to display the mobile version of the site on the desktop?

Question

HTML

There is a site with an adaptive, it works properly. But under a certain condition, the site should be displayed only in the mobile version, regardless of the device, how to do this?

I tried to set a fixed value for the width, but there is no effect

<meta name="viewport" content="width=500, initial-scale=1" />

PS The application is written in React + StyledComponents

Answer 1

And if you display in an iframe ?

Answer 2

You must have more than one code on the mobile version of css, so that it is displayed on the desktop as on mobile, change all css as on mobile.