[css-gaps-1] Update gap decoration behavior when gaps are coincident due to track collapsing w3c#11814 (w3c#13298)

Author: oSamDavis

css-gaps-1/Overview.bs

@@ -330,10 +330,10 @@ Layout and painting</h3>
 		grid/subgrid/fragmentation/subgrid-gap-decorations-fragmentation-018.html
 	</wpt>
 
-	If the positions of one or more gaps coincide exactly due to being [=collapsed gutter|collapsed=],
-	at most one decoration will be drawn for that set of gaps.
-	The decoration that is drawn is selected according to the
-	<a href="https://www.w3.org/TR/CSS2/tables.html#border-conflict-resolution">border conflict resolution</a> rules for tables.
+	Gap decorations are [=assigned gap decoration values|assigned=] after [=gutter collapsing|collapsed gutter=] has been applied.
+	A given set of [=collapsed gutters=] consume exactly one [=gap decoration=]; the next [=gap decoration=]
+	is applied to the next gutter (or set of [=collapsed gutters=]). Therefore, [=collapsed gutters=] are treated as a
+	single gutter for decoration purposes.
 
 <!-- Big Text: rule-break 
 
@@ -1685,5 +1685,8 @@ Changes since the <a href="https://www.w3.org/TR/2025/WD-css-gaps-1-20250417/">1
 			<a href="https://github.com/w3c/csswg-drafts/issues/12848">Issue 12848</a>,
 			<a href="https://github.com/w3c/csswg-drafts/issues/8402">Issue 8402</a>)
 		<li>Added a paragraph clarifying that gap decorations are not drawn where gaps are suppressed due to fragment breaks.
-		<li>Corrected syntax errors for the inset shorthands.</li>
+		<li>Corrected syntax errors for the inset shorthands.
+		<li>Updated the behavior for when gaps are coincident due to track collapsing.
+			(<a href="https://github.com/w3c/csswg-drafts/issues/11814">Issue 11814</a>)
+
 	</ul>