CKEditor 3.6 and later includes the Stylesheet Parser (
stylesheetparser) plugin that can be used to point to an external CSS stylesheet containing style definitions. It will help you use existing CSS styles and display them in the Styles drop-down list without a need to define them specifically for CKEditor as described here.
For more information on using the plugin refer to the Stylesheet Parser Plugin section of the Developer's Guide and check the "Stylesheet Parser plugin" (
stylesheetparser.html) sample from the
_samples folder of your CKEditor installation package.