Set delete target dim overlay color to black

styles/27-patterns-delete-confirmation.css

@@ -20,7 +20,7 @@
   content: "";
   position: absolute;
   inset: 0;
-  background: var(--color-dark-grey);
+  background: var(--surface-delete-confirmation-target-dim-overlay);
   opacity: var(--layout-delete-confirmation-target-dim-opacity);
   pointer-events: none;
 }