diff --git a/apps/web/src/app.css b/apps/web/src/app.css
index bb446c9..b72d333 100644
--- a/apps/web/src/app.css
+++ b/apps/web/src/app.css
@@ -39,7 +39,10 @@
 	--muted: oklch(0.27 0 0);
 	--muted-foreground: oklch(0.708 0 0);
 	--border: oklch(1 0 0 / 9%);
-	--grid-line: color-mix(in oklch, white 9%, var(--card));
+	/* Mixed against --muted, not --card: header/rowheader cells (bg-muted) sit
+	   on the grid's outer top and left edges, and a line tuned only for
+	   contrast against --card all but disappears there. */
+	--grid-line: color-mix(in oklch, white 9%, var(--muted));
 	--primary: oklch(0.92 0 0);
 	--primary-foreground: oklch(0.2 0 0);
 	--destructive: oklch(0.65 0.19 25);