We have a number of different themes on our website as we have different departments with different color styles. However, the only thing that changes are the colors of the sidebar and which menu is displayed on the sidebar; the layout of these pages remain the same almost exclusively. It seems as though having 16 different themes, which we do, is unnecessary if these are the only things changing (sidebar color and menu).
Are there any good modules which could achieve this functionality (changing color and menu depending on department) without having all these different themes? Or are themes the only/best way to go to achieve this functionality? Also is having this many themes the average or is that a lot?