[css-cascade-6] Clarify nested scopes and scope proximity

Author: mirisuzanne

css-cascade-6/Overview.bs

@@ -146,13 +146,17 @@ Cascade Sorting Order</h3>
 			Each declaration has the same specificity as the style rule it appears in.
 			The declaration with the highest specificity wins.
 
-		<dt id='cascade-proximity'><dfn>Scoping Proximity</dfn>
+		<dt id='cascade-proximity'><dfn>Scope Proximity</dfn>
 		<dd>
-			If two declarations both have elements
-			selected by scoped descendant relationships
-			applying [=scoping proximity=],
-			then the declaration with the fewest generational hops
-			between the ancestor/descendant element pair wins.
+			When comparing declarations that appear in style rules
+			with different [=scoping roots=],
+			then the declaration with the fewest
+			generational or sibling-element hops
+			between the [=scoping root=] and the
+			[=scoped style rule=] [=subject=] wins.
+			For this purpose,
+			style rules without a [=scoping root=]
+			are considered to have inifinite proximity hops.
 
 		<dt id='cascade-order'>Order of Appearance
 		<dd>
@@ -308,17 +312,14 @@ Effects of ''@scope''</h4>
 	* The [=cascade=] prioritizes declarations
 		with a [=scope proximity|more proximate=] [=scoping root=],
 		regardless of specificity or source order
-		by applying [=scoping proximity=]
-		between the [=scoping root=] and the [=subject=] of each [=scoped style rule=].
-		<!-- This causes declarations [insert appropriate sentence from issue below]. -->
+		by applying [=scope proximity=]
+		between the [=scoping root=] and the [=subject=]
+		of each [=scoped style rule=].
 
 	Note: Unlike <a href="https://www.w3.org/TR/css-nesting/">Nesting</a>,
 	selectors within an ''@scope'' rule
 	do not acquire the specificity of any parent selector(s) in the ''@scope'' prelude.
 
-	Note: For [[#scope-scope|nested @scope rules]],
-	only the innermost ''@scope'' matters for determining [=scoping proximity=].
-
 	<div class=example>
 		The following selectors have the same specificity (0,0,1):
 
@@ -334,7 +335,7 @@ Effects of ''@scope''</h4>
 		is not applied to the specificity of the scoped selector.
 		However, since one <{img}> selector is scoped,
 		that selector is weighted more strongly in the cascade
-		with the application of [=scoping proximity=].
+		with the application of [=scope proximity=].
 	</div>
 
 	<div class=example>
@@ -598,11 +599,23 @@ Scope Nesting</h4>
 
 	''@scope'' rules can be nested.
 	In this case, just as with the nested style rules,
-	the selectors of the inner ''@scope''
-	(including those defining its [=scope=])
+	the prelude selectors of the inner ''@scope''
+	(those defining its [=scope=])
 	are [=scoped selectors|scoped by=]
 	the selectors of the outer one.
 
+	Note: The resulting [=scope=]
+	for further nested [=scoped style rules=]
+	is practically constrained by both
+	the outer and inner ''@scope'' rules,
+	but the [=scoping root=] is defined
+	by the innermost ''@scope''.
+	Since [=scope proximity=] is measured
+	between a [=scoped style rule=] [=subject=]
+	and [=scoping root=],
+	only the innermost ''@scope'' matters
+	for determining [=scope proximity=] of [[#scope-scope|nested @scope rules]].
+
 	<div class=example>
 		When nesting ''@scope'' rules inside other ''@scope'' rules,
 		or inside other selectors,
@@ -704,14 +717,29 @@ Changes</h2>
 This appendix is <em>informative</em>.
 
 <h3 id="changes-2022-08">
-Changes since the 21 December 2021 First Public Working Draft</h3>
+Changes since the 21 March 2023 Working Draft</h3>
 
 	Significant changes since the
-	<a href="https://www.w3.org/TR/2021/WD-css-cascade-6-20211221/">21 December 2021 First Public Working Draft</a> include:
+	<a href="https://www.w3.org/TR/2023/WD-css-cascade-6-20230321/">21 March 2023 Working Draft</a> include:
+
+	* Clarified that [=scope proximity=] is a single measurement of the steps
+		between a single [=scoping root=] and [=scoped style rule=] [=subject=].
 
-	* Removed strong scoping proximity.
+	* Removed strong scope proximity.
 		(<a href="https://github.com/w3c/csswg-drafts/issues/6790">Issue 6790</a>)
 
+	* Removed the scoped descendant combinator (deferred).
+		(<a href="https://github.com/w3c/csswg-drafts/issues/8628">Issue 8628</a>)
+
+	* Added the {{CSSScopeRule}} interface.
+		(<a href="https://github.com/w3c/csswg-drafts/issues/8626">Issue 8626</a>)
+
+<h3 id="changes-2022-08">
+Changes since the 21 December 2021 First Public Working Draft</h3>
+
+	Significant changes since the
+	<a href="https://www.w3.org/TR/2021/WD-css-cascade-6-20211221/">21 December 2021 First Public Working Draft</a> include:
+
 	* Clarified ''@scope'' effects on nested '':scope'' and ''&'' selectors.
 		(<a href="https://github.com/w3c/csswg-drafts/issues/8377">Issue 8377</a>)
 
@@ -721,18 +749,12 @@ Changes since the 21 December 2021 First Public Working Draft</h3>
 	* Specified how name-defining [=at-rules=] behave in ''@scope''.
 		(<a href="https://github.com/w3c/csswg-drafts/issues/6895">Issue 6895</a>)
 
-	* Added the {{CSSScopeRule}} interface.
-		(<a href="https://github.com/w3c/csswg-drafts/issues/8626">Issue 8626</a>)
-
 	* Added implicit scopes by making ''<<scope-start>>'' optional.
 		(<a href="https://github.com/w3c/csswg-drafts/issues/6606">Issue 6606</a>)
 
 	* Disallowed [=pseudo-elements=] in the ''@scope'' prelude.
 		(<a href="https://github.com/w3c/csswg-drafts/issues/7382">Issue 7382</a>)
 
-	* Removed the scoped descendant combinator (deferred).
-		(<a href="https://github.com/w3c/csswg-drafts/issues/8628">Issue 8628</a>)
-
 	* Removed selector scoping notation.
 		(<a href="https://github.com/w3c/csswg-drafts/issues/7709">Issue 7709</a>)