[css-overflow-3] Per resolution, ignore overflow-clip-edge:border-box. #10745

Author: tabatkins

css-overflow-3/Overview.bs

@@ -664,9 +664,13 @@ Expanding Clipping Bounds: the 'overflow-clip-margin' property</h3>
 	and [[css-backgrounds-3#shadow-shape]],
 	noting in particular the formula for outsets beyond the [=border edge=].
 
-	If the box is a [=scroll container=],
-	the [=overflow clip edge=] is clamped to stay within the element's [=padding box=].
-	(This does not affect the [=computed value|computed=] or [=used value=] of this property.)
+	If the box is a [=scroll container=]:
+
+	* the [=overflow clip edge=] is clamped to stay within the element's [=padding box=].
+		(This does not affect the [=computed value|computed=] or [=used value=] of this property.)
+	* the ''border-box'' value
+		behaves as ''padding-box''
+		and ignores any specified offset.
 
 	Note: This property was previously defined to only affect ''overflow: clip''.
 	It now also affects [=scroll containers=],