[css-contain-2][editorial] Consistently refer to containments being on or off, independently of the value of 'contain'.

Author: tabatkins

css-contain-2/Overview.bs

@@ -423,9 +423,8 @@ Strong Containment: the 'contain' property</h2>
 		''contain: strict'' can be applied to communicate further restrictions.
 	</div>
 
-	Additionally, when the [=used value=] of the 'contain' property
-	on either the HTML <{html}> or <{body}> elements
-	is anything other than ''contain/none'',
+	Additionally, when any [=containments=] are active
+	on either the HTML <{html}> or <{body}> elements,
 	propagation of properties
 	from the <{body}> element
 	to the [=initial containing block=], the viewport, or the [=canvas background=],
@@ -483,6 +482,12 @@ Strong Containment: the 'contain' property</h2>
 	of properties set on the <{html}> element itself
 	is unaffected.
 
+	Note: Several properties beyond 'contain' can turn on various [=containments=] for an element.
+	These do not affect the value of 'contain';
+	an element can have ''contain: none''
+	but still have [=layout containment=] turned on by 'content-visibility',
+	for example.
+
 <h2 id='containment-types'>
 Types of Containment</h2>
 
@@ -497,6 +502,7 @@ Types of Containment</h2>
 	affect what they are introducing,
 	and include in their specification any effect not described here.
 
+
 <h3 id='containment-size'>
 Size Containment</h3>
 
@@ -1233,10 +1239,9 @@ Suppressing An Element's Contents Entirely: the 'content-visibility' property {#
 
 		: <dfn>auto</dfn>
 		::
-			The user agent must change the [=used value=] of the 'contain' property
-			so as to turn on [=layout containment=],
+			Turns on [=layout containment=],
 			[=style containment=],
-			and [=paint containment=].
+			and [=paint containment=] for the element.
 
 			If the element is not [=relevant to the user=],
 			it also [=skips its contents=].