THE HOMEPAGE IS SACRED!
  
So, one strategy that should be considered, is to make the hompage an independant entity by itself -and add inline CSS so there is no chance of it not fulling loading completely while waiting for another file that for whatever reason is slow or giving a 404 error or whatever....or loading to an ugly unformated default once timedout!

External CSS can be used for the other pages – if they are not EXTREMELY vital...

Another strategy that has worked was to add those SAME external CSS links Twice in the code fo the individual pages – to lessen the odds.

Also, now there are new SEO concerns with the DIV tag using the Hidden attribute – and what could be interpreted by new Search Engine Technology – so perhaps, if there are Hidden attributes, an external javascript could be used – and if on a Windows Server – .asp – so the code can not be opened by competitors.

My solution to this is to have a site-wide css file... and a directory wide file, and a page-specific file.
Too hard to remember to include the link to the file on each page.
I generate pages in php and it checks to see if appropriate files exist.
All I have to do then is name the css files according to the correct naming scheme.
Easy peasy :)