[css-cascade] mention what it means to not apply, add explicit ID w3c#1861

Author: fantasai

css-cascade-3/Overview.bs

@@ -431,7 +431,7 @@ Used Values</h3>
 
 	The <dfn export>used value</dfn> is the result of taking the <a>computed value</a>
 	and completing any remaining calculations to make it the absolute theoretical value
-	used in the layout of the document.
+	used in the formatting of the document.
 
 	<p class='example'>
 		For example, a declaration of ''width: auto'' can't be resolved into a length without knowing the layout of the element's ancestors,
@@ -442,10 +442,11 @@ Used Values</h3>
 		As another example, a <code>&lt;div></code> might have a computed 'break-before' value of ''auto'',
 		but acquire a used 'break-before' value of ''break-before/page'' by propagation from its first child. [[css-break-3]]
 
-	If the property does not <dfn lt="apply to | applies to">apply to</dfn>
-	this element or box type
-	(as defined by its “Applies To” line),
-	then it has no <a>used value</a> for that property.
+	If a property does not <dfn id="applies-to" lt="apply to | applies to">apply to</dfn>
+	this element or box type--
+	as noted in its “Applies to” line--
+	then it has no formatting effect on that type of box or element,
+	and therefore has no <a>used value</a> for that property.
 
 	<p class='example'>
 		For example, the 'flex' property has no <a>used value</a>

css-cascade-4/Overview.bs

@@ -545,7 +545,7 @@ Used Values</h3>
 
 	The <dfn export>used value</dfn> is the result of taking the <a>computed value</a>
 	and completing any remaining calculations to make it the absolute theoretical value
-	used in the layout of the document.
+	used in the formatting of the document.
 
 	<p class='example'>
 		For example, a declaration of ''width: auto'' can't be resolved into a length without knowing the layout of the element's ancestors,
@@ -556,10 +556,11 @@ Used Values</h3>
 		As another example, a <code>&lt;div></code> might have a computed 'break-before' value of ''auto'',
 		but acquire a used 'break-before' value of ''break-before/page'' by propagation from its first child. [[css-break-3]]
 
-	If the property does not <dfn lt="apply to | applies to">apply to</dfn>
-	this element or box type
-	(as defined by its “Applies To” line),
-	then it has no <a>used value</a> for that property.
+	If a property does not <dfn lt="applies to | apply to">apply to</dfn>
+	this element or box type--
+	as noted in its “Applies to” line--
+	then it has no formatting effect on that type of box or element,
+	and therefore has no <a>used value</a> for that property.
 
 	<p class='example'>
 		For example, the 'flex' property has no <a>used value</a>