Although ... looked into colour blindness issues, you try getting some colour combinations to work, not going to happen. eg #808000 background, no foreground colour would get past all colour blindness issues.
My answer, well if I had colour blindness, i'd run the broswer with its own stylesheet.
So keep your styling in the stylesheets.
ACCESSIBILITY can be a pain in the.. but, it's not so much as your site can't have this or that. It's just your site has to be "ACCESSIBILE", so as long as it downgrades you should be ok.
Looking at a site I have with the skiplink I mention above, I use it with display:none works fine in text readers, opera voice reads it, Jaws ignores it!
Also use a dropdown like sukerfish menus, Tabbing won't drop the menu down.
My answer, sorry not changing it, turn the style sheet off, the site is accessible with stylesheets on or off and the order pages work. No it's not as pretty with stylesheets off, BUT ITS STILL ACCESSIBILE.
And it looks exactly the same as it did before.
All that work and it looks the same. Why don't I feel good!
My dim brain even thought this: "I don't sell products suitable for the disabled."
Hmm, wonder if the disabled ever buy gifts for able bodied friends ;)
It's all about more customers/visitors.