Retro emulator lets you see backward compatibility with older versions of Internet Explorer (IE5, IE6, IE7 IE8), Netscape Navigator, FireFox, Opera, LYNX, Safari etc. After that you will see your website in the mobile view mode like this. Please note that everything you modify in this VM will be discarded, nothing is saved. This helps developers or QA testers to run a quick check of how their code appears on Firefox, as part of their development lifecycle.
For example, a Firefox emulator will provide the same look and feel of an actual Firefox browser when a website is opened on it.