Explanation/Reference:
Responsive layout groups and grids
The Responsive UI was introduced in Version 7.1, and has now been enhanced in two areas, to create an entirely responsive UI.
PRPC 7.1.4 introduces the Layout Group control, which can render its contents as "tabs," "accordions,"

or as a "menu." The rendering choice is driven through the presentation layout (the skin), which presents the information responsively: a "tab" at a certain breakpoint can turn into an "accordion" or a dropdown-style menu, depending upon what format would be most appropriate for the device/screen size being used.
The grid functionality has been enhanced, so that grids may be displayed on a tablet or a phone without

the need for horizontal scrolling, offering the optimum experience on a mobile device. A PRPC Grid Layout now supports responsive breakpoints in the skin definition in which columns can drop off or be consolidated according to screen size.
References: https://pdn.pega.com/release-note/responsive-layout-groups-and-grids