Abstract: A computer system enables users to specify a plurality of cards that comprise a design interface or presentation, each card being renderable in a simulation or production environment, separate from other cards of the plurality of cards. The user can specify one or more sections or groupings of cards, where each section or grouping includes multiple cards. The user can specify multiple flow connections, including at least a first flow connection from one of the plurality of cards to a first section, where the cards of the first flow connection are not part of the first section. During a simulation rendering of the design interface, individual cards are rendered in a sequence that is based at least in part on one or more of the flow connections, including at least the first flow connection.