My original intent was to encapsulate that in StyleSheet, however there are some complexities to support skins set at the page level, and user skins. In mojoBasePage we set the skins with allowOverride = false while in SiteHome it is true. SiteHome is used for all content system pages but other pages in the site inherit from mojoBasePage besides the content pages. This way pages outside the ocntent system use the site default skin by default.
I am doing some work for a customer to better enable partitioning sections of a site to use specific skins and to give them the appearance of being separate sites even though they are really sections within a site. That is also going to impact the implementation of stylesheets so once I have that all worked out I will tidy up the code a little, I admit its not the prettiest thing right now but its because I'm still working on the ideas.
Joe