AC.UI is built on our time-tested UI.X platform for XenForo 2. We have thought through and carefully tuned AC.UI until it is truly the most modern and ideal interface for communities, and not a single detail has been overlooked. Every size of the frontend has been optimized for readability, every addition has been accounted for, navigation for mobile devices has been completely redesigned, and much more has been changed from the base XenForo for better user interaction and discoverability.