It isn't an abstract thing, it's HTML, and it behaves like HTML. That CSS styles HTML is not an implementation detail -- it is dependent on the underlying docu

It isn't an abstract thing, it's HTML, and it behaves like HTML. That CSS styles HTML is not an implementation detail -- it is dependent on the underlying document tree, not an abstraction of it. As I said before, floats do not change that (from the CSS2 spec): In the float model, a box is first laid out according to the normal flow, then taken out of the flow and shifted to the left or right as far as possible. Content may flow along the side of a float. What you're asking is to be able to modify the document tree, which modifies the normal flow, and then have something which explicitly depends on the rendering of the normal flow to not change.