I think it's due to some default of some sort on padding, or possibly that the default column width in Timeless doesn't match that of Vector (or that it does and that because of the 3-column layout it probably shouldn't). If I zoom out from 100% just once with the default widths of a responsive reference list on en.WP, the columns become obvious, so it's clear to me the list is getting the columns styling. It's just that at my default resolution, I almost always have one column where I probably should have two.
(supporting earlier conversation: See thread at my talk page.)