A layout manager can generate a layout for displaying a plurality of content units in a display area using a layout strategy, with the layout strategy specifying a layout design rule. The generated layout can indicate a position in the display area for the plurality of content units. In some embodiments, the design rule(s) may in effect “codify” traditional graphic design principles. When the layout is generated, the content units can be placed into a display area of a page and then the layout can be checked against at least one design rule and the layout adjusted as needed to meet the design rule. The system can comprise a user interface module that renders the content units in the display area using the generated layout. In some embodiments, content units are placed into a layout on a one-by-one basis according to priority, available display space, and one or more design rules.