lucy24 - 1:32 pm on Jul 20, 2013 (gmt 0)
What _I_ can't figure out is why, if you remove the width constraint on the wrapper and widen the window, float 4 ends up under float 3 instead of under float 1-- and now there's no intervening vertical space.
Belated "D'oh!" moment as I figure out that it's precisely the extra height of #2 that makes this happen. #4 on a line by itself can't go any further to the left, because it starts out in line with #3 and therefore is blocked by #2.
It is easier to see in action if you make all four of them different colors ;)