diff --git a/src/pages/index.astro b/src/pages/index.astro
index 32c82b7..5d63c75 100644
--- a/src/pages/index.astro
+++ b/src/pages/index.astro
@@ -652,7 +652,16 @@ const socialImage = new URL('/og.png?v=3', Astro.site);
        THIS VALUE IS PER GLYPH, NOT PER FONT. It was 0.078em while line one opened on
        an R (bearing 0.076em); reusing that figure for the S over-pulled the headline
        by 4px and the scroller clipped the bowls flat. Re-measure whenever the first
-       word of the headline changes. */
+       word of the headline changes.
+
+       What it should be is S_inkLeft - W_inkLeft * (mission size / headline size); in
+       Public Sans that is 0.05352 - 0.02320 * ratio, which runs 0.0464-0.0502em across
+       the whole clamp, so one fixed 0.05em covers every breakpoint to within half a
+       pixel. Confirmed by scanning the two printed edges out of a 4x screenshot: the
+       mission lands 0-1px right of the headline at sixteen viewports from 320 to 2560
+       wide, the same scatter the previous face measured, and the residue is the ink
+       threshold catching 15px secondary-grey type a hair later than a 130px bright
+       one. Do not chase it with a per-breakpoint inset. */
     --optical-inset: 0.05em;
 
     display: grid;