'line-height' values less than 1em or so does not work. The relevant part of the CSS1 spec is 4.4: "Note that this doesn't preclude the text on two adjacent lines from overlapping each other. The 'line-height' may be smaller than the height of the text, in which case the leading will be negative. This is useful if you know that the text will contain no descenders (e.g., because it only contains uppercase), so the lines can be put closer together."

Using 2/11 build, verified fixed.