[css-cascade-5] Put preshint rules into their own author layer. w3c#5856

Author: fantasai

css-cascade-5/Overview.bs

@@ -1413,18 +1413,18 @@ Precedence of Non-CSS Presentational Hints</h3>
 	for example the <code>bgcolor</code> attribute or <{s}> element in [[HTML]].
 	All document language-based styling must be translated to corresponding CSS rules
 	and either enter the cascade as [=UA-origin=] rules or
-	be treated as [=author-origin=] rules with a specificity of zero
-	placed at the start of the [=author style sheet=].
+	be treated as [=author-origin=] rules in their own [=cascade layer=]
+	placed as the lowest [=layer=] in the [=author origin=].
 	A document language may define whether such a presentational hint
 	enters the [=cascade=] as [=UA-origin=] or [=author-origin=];
 	if so, the UA must behave accordingly.
-	For example, [[SVG11]] maps its presentation attributes into the author level.
+	For example, [[SVG11]] maps its presentation attributes into the [=author origin=].
 
 	Note: Presentational hints entering the [=cascade=] as [=UA-origin=] rules
 	can be overridden by [=author-origin=] or [=user-origin=] styles.
 	Presentational hints entering the cascade as [=author-origin=] rules
 	can be overridden by [=author-origin=] styles,
-	but not by non-important [=user-origin=] styles.
+	but not by non-[=important=] [=user-origin=] styles.
 	Host languages should choose the appropriate origin for presentational hints
 	with these considerations in mind.