Hope your analysis yields interesting fruit, and that it makes it to a forthcoming front page. My hunch is yours, I've noticed that what I perceive as "pleasing" vertical indent for example can usually be expressed exactly as a continued fraction expansion. Which is a totally straightforward heuristic to implement by hand or programmatically: define a hierarchy of tags, then for each element in the block of priority N multiply the 0th element's height by some fractional constant N times. In practice this seems to work pretty well, there's a lot more features latent in a block of text than just vertical whitespace though and the ideal way to split the prescribed amount of whitespace between margin-top and padding-top attributes isn't obvious to me.