With the responsive design feature activated, your Ecwid store will be automatically optimized for mobile devices (smartphones, tablets, gaming consoles, etc.). Your store will dynamically adapt to the size of a visitor’s screen. This means that mobile users will have a better buying experience that will help to increase your mobile sales. Read the post in the Ecwid Blog to learn How Responsive Design Increases Mobile Sales.
Source: Second Notice: Mobile Design Will Be Enabled For Your Ecwid Store