[css-cascade-5] Clarify where @layer can be placed, and what actually gets ignored. w3c#6522

Author: fantasai

css-cascade-5/Overview.bs

@@ -124,7 +124,7 @@ Importing Style Sheets: the ''@import'' rule</h2>
 		as if they were written literally into the stylesheet at the point of the ''@import''.
 
 	Any ''@import'' rules must precede all other valid at-rules and style rules in a style sheet
-	(ignoring ''@charset'' and empty ''@layer'' definitions),
+	(ignoring ''@charset'' and empty ''@layer'' definitions)
 	and must not have any other valid at-rules or style rules between it and previous ''@import'' rules,
 	or else the ''@import'' rule is invalid.
 	The syntax of ''@import'' is:
@@ -1613,9 +1613,13 @@ Declaring Without Styles: the ''@layer'' statement at-rule</h5>
 		@layer <<layer-name>>#;
 	</pre>
 
-	Such empty ''@layer'' rules are allowed before and after ''@import'' and ''@namespace'' rules,
-	but are not allowed between (or intermixed with) ''@import'' and ''@namespace'' rules,
-	and must not precede any ''@charset'' rule.
+	Such empty ''@layer'' rules are allowed before ''@import'' and ''@namespace'' rules
+	(after the ''@charset'' rule, if any)
+	as well as everywhere ''@layer'' [=block at-rules=] are allowed.
+
+	Note: They are not allowed between (or intermixed with) ''@import'' and ''@namespace'' rules,
+	and such interleaved ''@layer'' rules will cause any subsequent ''@import'' or ''@namespace'' rules
+	to be ignored.
 
 	Unlike the [[#layer-block|block syntax]],
 	multiple comma-separated layer names can be provided in this syntax,