1. A method of managing cascading style sheet rules, comprising: identifying a markup page of content items; designating a plurality of super-themes by: defining a first markup element that associates at least one content item of the markup page with a first cascading style sheet class; designating the first markup element by a first super-theme; defining a second markup element that associates at least one content item of the markup page with a second cascading style sheet class different from the first cascading style sheet class; designating the second markup element by a second super-theme; loading a common cascading style sheet for the markup page; automatically modifying, by a processor, the common cascading style sheet to use the first super-theme as a parent selector for at least one cascading style sheet rule applied to at least one content item within the first super-theme designated markup element; and automatically modifying, by the processor, the common cascading style sheet to use the second super-theme as a parent selector for at least one cascading style sheet rule applied to at least one content item within the second super-theme designated markup element.