ability to add a CSS class to each element

Maybe I'm missing something, but it would be nice to be able to specify a CSS class to each of the actual DOM elements that are generated by the collection (since the DOM structure that is generated seems internal and I don't want to rely on the specific number of nested divs that are generated.
I can apply my class to an element inside the collection, but it makes it harder to do things like add a margin between each element.