The Experience manager allows you to preview the pages of a channel for a number of viewport widths, in order to get an idea of how the website will look on devices other than a monitor, such as tablets or smartphones. By default, the Experience manager provides the following set of viewport widths:
Responsive (unbound, page reflows when resizing the window or opening side panels)
Desktop (defaults to 1280px)
Tablet (defaults to 720px)
Smartphone (defaults to 320px)
You can select from these viewport widths using the drop-down in the center of the Experience manager's toolbar.
This is what the page looks like from tablet view:
This is what the page looks like from phone view: