alt131 - 9:04 pm on Jan 31, 2012 (gmt 0)
Hi Nyteshade, thanks for a very interesting post. It may not seem productive given you circled back to the start, but it's been really interesting watching your thinking evolve, and I know you will have learned so much as well. It's about personal coding goals, but I really appreciate the importance you've given to accessibility, and I personally believe that a coder develops better coding practises if they start thinking about it from the beginning.
Regrettably the "gotcha" - as you identified - has been connecting splitting css files with increasing accessibility. There isn't a connection, and as we've discussed, splitting shouldn't really be necessary on such a small site. I think the splitting idea was further complicated by Keith's principles - I'm still a bit baffled by them, for all the reasons already given.
Changing styles for accessibility reasons is a different issue, and the css isn't split on a property/value basis as Keith was suggesting. The split is on the basis of the property/values you want to over-ride when a user selects a particular style/sheet. You've probably already figured this out, but it's not about putting the padding for an element in one file and the margins in another for organisational purposes. It's about identifying that (as an eg) you want very high contrast/large fonts, so you want nil back-ground images, a different font-colour and an increased font size.
Less about splitting the css at the property/value level, more about identifying the styles that need to be adjusted to achieve the desired outcome. (Form versus function again ;) ) Sure, you may need to adjust the margins/padding as well, but this isn't about organising them into different files, it's about over-riding the initial design.
I think its great you've figured users can (and frequently do) set their own browser preferences. A good reminder that style facilitates the delivery of content ;) Second, "best" practise to always keep in mind things like font-size, colour contrast ratios and the size of targets (like links etc) to achieve maximum accessibility - which frequently improves usability anyway.
Third, this is your own small site and you are interested in this, so I would encourage you to keep exploring providing basic assistance without trying to predict every user need. Things that will accomodate a wider range of issues, like a means to increase text-size. You might also investigate an "extreme" switch that strips out most of the layout leaving a very high contrast font/background and large fonts. Never a pretty design result, but covers a wide range of user needs and from a coding perspective, a good test of how well the content has been structured as well.
g* "style sheet switching" for different techniques - plus ideas of things to consider. And of course, back here with questions - or even just to keep us informed about this interesting progression.