Looks like you replied to a very old thread from 2015. Since then, much progress has occurred in our mobile-responsive design implementation:
Our new responsive cart v.2 entered public beta testing in February 2017, was significantly improved later that May and ended its beta phase to became the default cart for all new clients, then was overhauled yet again to an all-new responsive cart v.3 back in March of this year, which became the standard cart for all clients, new and old alike, effective this past June.
If you are not seeing our responsive new cart in your site, you may have taken steps to deliberately override it with our classic cart v.1 if your site had issues with an early beta version of the new cart, or if you were using cart-customization code to alter the appearance of that classic cart v.1 (most of which the new cart v.3 now supports via other means, with settings in your Dashboard). Make sure the E-junkie Cart Script code in your site's sales pages load our standard
box.js cart-overlay script, rather than the
box_fb_o.js alteration you may have made to force-load the classic cart v.1. This is our standard Cart Script code you should have in your sales pages to display the responsive new cart: