[css-ui-4] w3c#8649 Specify ink overflow extent for outline

css-ui-4/Overview.bs

@@ -75,6 +75,7 @@ spec:css2; type:property; text:top
 spec:css2; type:property; text:right
 spec:css2; type:property; text:visibility
 spec:css2; type:property; text:z-index
+spec:css-overflow-3; type:dfn; text:ink overflow area
 spec:css-pseudo-4; type:selector; text:::before
 spec:css-pseudo-4; type:selector; text:::after
 spec:css-pseudo-4; type:selector; text:::first-line
@@ -250,6 +251,7 @@ Outline properties</h2>
 
 	<ol>
 		<li>Outlines do not take up space.
+		<li>Outlines contribute to [=ink overflow area=].
 		<li>Outlines may be non-rectangular.
 		<li>UAs often render outlines on elements in the '':focus-visible'' state.
 	</ol>
@@ -314,6 +316,9 @@ Outline properties</h2>
 
 	The position of the outline may be affected by descendant boxes.
 
+	The dimensions of the drawn outline contribute to the
+	[=ink overflow area=] of an element.
+
 	User agents should use an algorithm for determining
 	the outline that encloses a region appropriate
 	for conveying the concept of focus to the user.