When you resize a browser to check whether your site will work on mobile, that’s only half the picture. Most responsive check sites use a sized iframe to simulate phones. But, to get an accurate view of what your site will look like, you need to make sure that in addition to setting the viewport, you also pass the correct user-agent so that sites that have mobile versions know what version to send.
Using the Thum.io website screenshot generator, StayResponsive renders multiple versions of a website using proper user-agent strings and viewport sizes. Take a look at our results:
With user-agent and viewport set