This is the first block, with a big left margin. At the end
of this block is a left float which should be square. Text that
follows this box should flow to the right of the float or go below
it; no text should be on the left of the float.
the square left float.
This is the second block. It is sized so as to be just
wide enough to slightly overlap the float. Text shouldn't be able
to fit around the float without overflowing this box, so instead
all the text should just move below the float.