[css-gaps-1] Specify behavior with collapsed gutters. #11814

Author: kbabbitt

css-gaps-1/Overview.bs

@@ -177,6 +177,11 @@ Layout and painting</h3>
 	<a>Gap decorations</a> are painted relative to pairs of <a>gap intersection points</a>,
 	in the center of the corresponding gap and parallel to its edges.
 
+	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.
+
 <h3 id="break">
 Breaking gap decorations into segments: The 'column-rule-break', 'row-rule-break', and 'rule-break' properties</h3>
 
@@ -938,3 +943,14 @@ No new privacy considerations have been reported on this specification.
 Security Considerations</h2>
 
 No new security considerations have been reported on this specification.
+
+<h2 id="changes">
+Changes</h2>
+
+<h3 id="changes-20250417">
+Changes since the <a href="https://www.w3.org/TR/2025/WD-css-gaps-1-20250417/">17 April 2025 Working Draft</a></h3>
+
+	<ul class="non-normative">
+		<li>Specified the behavior when gaps are coincident due to track collapsing.
+			(<a href="https://github.com/w3c/csswg-drafts/issues/11814">Issue 11814</a>)
+	</ul>

css-grid-2/Overview.bs

@@ -4128,7 +4128,7 @@ Gutters: the 'row-gap', 'column-gap', and 'gap' properties</h3>
 	(In particular, there is no <a>gutter</a> between the first/last track of the <a>implicit grid</a>
 	and the “auto” lines in the <a>augmented grid</a>.)
 
-	When a <a>collapsed track</a>’s gutters <dfn lt="collapsed gutter">collapse</dfn>,
+	When a <a>collapsed track</a>’s gutters <dfn export lt="collapsed gutter">collapse</dfn>,
 	they coincide exactly--
 	the two gutters overlap so that their start and end edges coincide.
 	If one side of a <a>collapsed</a> track does not have a gutter