Nik - Ive been through this recently and unfortunately, Bob's reply is mostly right - BUT;
1.) Not everything that works in Mobile Safari, works in DPS. (i.e. Position:fixed divs) I hear this mantra over and over again. Not entirely valid.
2.) Ive been told by Adobe GOLD support that there is no definitive documentation specific to HTML handling.
Ive spent many hours working with HTML/JQuery/CSS3 articles (not as overlays, but actual articles) and support in DPS doesnt seem entirely there yet.
But he is dead on when he says if it doesnt work in Mobile, it wont work in DPS.
Hope that helps.