[css-cascade] level sync

Author: fantasai

css-cascade-3/Overview.bs

@@ -142,6 +142,9 @@ Conditional ''@import'' Rules</h3>
 	The evaluation and full syntax of the <a>import conditions</a>
 	is defined by the <a href="https://www.w3.org/TR/css3-mediaqueries/">Media Queries</a> specification [[!MEDIAQ]].
 
+<h3 id=import-processing>
+Processing Stylesheet Imports</h3>
+
 	When the same style sheet is imported or linked to a document in multiple places,
 	user agents must process (or act as though they do) each link
 	as though the link were to an independent style sheet.

css-cascade-4/Overview.bs

@@ -739,6 +739,7 @@ Filtering</h2>
 
 		<li>
 			It belongs to a style rule whose selector matches the element. [[!SELECT]]
+			(Taking <a href="https://www.w3.org/TR/selectors4/#scoping">scoping</a> into account, if necessary.)
 
 		<li>
 			It is syntactically valid: