> I'm hard pressed to believe the quality of the CSS across 15 subcontractors was actually good and consistent. You can't get 5 developers in a room without finding at least a few differences in opinion how something could or should be done and when it comes to CSS you have even more flexibility to how you're writing it and the associated markup.
Quality across more than 1 subcontractor for ANYTHING is rarely good. But the most important thing when dealing with large projects divided with multiple groups? Ownership. You make one group own the design / CSS. Then when others change their CSS it runs through them for reviews but they also supply guidelines for being consistent, etc.
It's almost impossible to handle disparate groups without having centralized owners and people who create guidelines on how to do everything so it's consistent.