[css-scoping-1] Define that tree-scoped names inherit into descendant shadow trees. #5693 #1995

Author: tabatkins

css-scoping-1/Overview.bs

@@ -21,6 +21,7 @@ spec:dom; type:dfn;
 	text:root; for:tree
 	text:find slottables
 	text:find flattened slottables
+	text:element; for:/
 spec:html; type:element; text:style
 spec:selectors-4; type:dfn;
 	text: static profile
@@ -69,7 +70,7 @@ Default Styles for Custom Elements</h2>
 	to create a stylesheet of "default element styles" for a given element.
 	This stylesheet applies across the entire document,
 	in all <a>shadow trees</a>,
-	and the rules in it apply at the <a>user agent origin</a>,
+	and the rules in it apply at the <a>user-agent origin</a>,
 	so author-level rules automatically win.
 
 	{{Window}}s gain a private slot <dfn attribute for=Window>\[[defaultElementStylesMap]]</dfn>
@@ -80,7 +81,7 @@ Default Styles for Custom Elements</h2>
 
 	Note: This implies, in particular,
 	that they apply to all <a>shadow trees</a> in every document,
-	and that the declarations in them are from the <a>user agent origin</a>.
+	and that the declarations in them are from the <a>user-agent origin</a>.
 
 	For the purpose of the <a>cascade</a>,
 	these stylesheets are ordered after the user agent's own stylesheets;
@@ -528,6 +529,15 @@ Slots and Slotted Elements in a Shadow Tree</h4>
 	and any deeper <a>slots</a> that their <a>slot</a> gets assigned to,
 	don't affect inheritance.
 
+<!--
+████████ ████████  ████████ ████████          ██████   ██████   ███████  ████████  ████████ ████████
+   ██    ██     ██ ██       ██               ██    ██ ██    ██ ██     ██ ██     ██ ██       ██     ██
+   ██    ██     ██ ██       ██               ██       ██       ██     ██ ██     ██ ██       ██     ██
+   ██    ████████  ██████   ██████   ███████  ██████  ██       ██     ██ ████████  ██████   ██     ██
+   ██    ██   ██   ██       ██                     ██ ██       ██     ██ ██        ██       ██     ██
+   ██    ██    ██  ██       ██               ██    ██ ██    ██ ██     ██ ██        ██       ██     ██
+   ██    ██     ██ ████████ ████████          ██████   ██████   ███████  ██        ████████ ████████
+-->
 
 <h3 id='shadow-names'>
 Name-Defining Constructs and Inheritance</h3>
@@ -555,7 +565,7 @@ Name-Defining Constructs and Inheritance</h3>
 	and doesn't give surprising results.
 
 	If an at-rule or property defines a name that other CSS constructs can refer to it by,
-	such as a 'font-family!!descriptor' name
+	such as a ''@font-face'' '@font-face/font-family!!descriptor' name
 	or an ''@keyframes'' name,
 	it must be defined as a <dfn export for=CSS>tree-scoped name</dfn>.
 	[=Tree-scoped names=] are "global" within a particular [=node tree=];
@@ -576,8 +586,13 @@ Name-Defining Constructs and Inheritance</h3>
 
 	Whenever a [=tree-scoped reference=] is dereferenced
 	to find the CSS construct it is referencing,
-	only the [=tree-scoped names=] associated with the same [=root=]
+	first search only the [=tree-scoped names=] associated with the same [=root=]
 	as the [=tree-scoped reference=] must be searched.
+	If no relevant [=tree-scoped name=] is found,
+	and the [=root=] is a [=shadow root=],
+	then repeat this search in the [=root=]'s [=host=]'s [=node tree=].
+	(In other words, [=tree-scoped names=] "inherit" into descendant shadow trees,
+	so long as they don't define the same name themselves.)
 
 	<div class=issue>
 		TODO: Fix all the at-rules that define global names,
@@ -596,7 +611,7 @@ Name-Defining Constructs and Inheritance</h3>
 <h4 id='shadow-names-serialization'>
 Serialized Tree-Scoped References</h4>
 
-	If a [=tree-scoped reference=] is [=serialized=],
+	If a [=tree-scoped reference=] is serialized,
 	it serializes only its value;
 	the associated [=root=] is lost.