Understanding Responsive Design. Responsive Web Design is simply a design of a website that changes its layout according to different screen sizes to fit the content properly when it comes to a desktop, smartphones, tablets, and other mobile devices. In this definition, there is a keyword here "properly" – In this context, "properly", means consistent. While working on a responsive design, the web developers have to make sure that the user experience of a website remains consistent throughout all the devices, irrespective of their screen size. (Source: nopCommerce Blog)
The number of mobile devices is increasing at a very fast pace and due to different screen sizes/screen resolution, a responsive design approach is used by web developers to keep the user experience the same or similar across the website.
Yes, nopCommerce default layout/theme does support a responsive design that is optimized for all screen sizes, and this approach is handled via media-queries in the CSS. This allows your online eCommerce store layout to display the content of your website by automatically adjusting the viewing area depending on the size of the screen.
Viewing the responsive design. Just re-size your browser windows and keep decreasing its size. As the size of the browser windows will decrease, you will see the nopCommerce site will adjust the content accordingly.