As mentioned above, the short answer is no. But I'm in need of something similar in the app I'm working on now, yet the areas where the CSS needs to be different are limited to very specific areas of a page.
If you're like me and don't need to serve up an entirely different stylesheet, another option would be to detect a device running iOS in the way described in this question's selected answer: Detect if device is iOS
Once you've detected the iOS device you could add a class to the area you're targeting using Javascript (eg. the document.getElementsByTagName("yourElementHere")[0].setAttribute("class", "iOS-device");, jQuery, PHP or whatever, and style that class accordingly using the pre-existing stylesheet.
.iOS-device {
style-you-want-to-set: yada;
}