Floats and clear in vertical text

float: left and float: right are line-relative: in vertical-rl and vertical-lr the line-left side is the physical top and the line-right side the physical bottom, whatever the direction.

Alpha Beta Gamma Delta Epsilon Zeta Eta Theta Iota Kappa.

float: left - pinned to the physical top; the columns beside it start below it

Alpha Beta Gamma Delta Epsilon Zeta Eta Theta Iota Kappa.

float: right - pinned to the physical bottom; the columns beside it stop above it

Alpha Beta Gamma Delta Epsilon Zeta Eta Theta Iota Kappa.

vertical-lr with direction: rtl - the top float is still float: left; both sides at once
A
B
clear: left - B is moved past the block-end edge of the float (the gap); A, uncleared, ignores it