White On Black VF is a special-purpose variable font with just one glyph (㊎) demonstrating an issue related to the non-zero winding rule used for rendering fonts. The issue is especially problematic when negative glyphs are reversed out of a positive background shape. The weight axis also shows how the technique for avoiding the problem with static fonts – removing overlaps – isn’t a viable solution for variable fonts because the topology of overlapping shapes may change across variations. The counterpart font, Black On White VF, is made with the same shapes but with an additional circular path, showing how the issue is not present with more typical positive-on-negative glyphs. The fonts were produced by Ken Lunde using a glyph designed by Ryoko Nishizuka.