I'm seeing that some of the demos stack page content when the browser window (viewport) is narrowed. The "Able", "Charity" and "Fresh" demos all exhibit this characteristic. How is this done? This can't be simply a transition to a website varient. That change is more instant. Have searched help and forum to no avail. Not even sure exactly what to search.

My site is http://www.aartvarkgrafix.com/aartvarkgrafix/pourhouse/