[css-values-5] No reason for per-element to delay random() resolution. Clarify the resolution timing, tho.

Author: tabatkins

css-values-5/Overview.bs

@@ -1093,12 +1093,22 @@ Generating a Random Numeric Value: the ''random()'' function</h3>
 		as lengths and angles are not the same type.
 	</div>
 
-	If ''per-element'' is not present in the <<random-caching-options>>,
-	a ''random()'' function can be [=simplify a calculation tree|simplified=]
+	A ''random()'' function can be [=simplify a calculation tree|simplified=]
 	as soon as its argument [=calculations=]
 	can be simplified to numeric values.
-	If ''per-element'' is specified in the <<random-caching-options>>,
-	the function cannot be simplified until [=used value=] time.
+
+	Note: This means that ''random()'' is <em>usually</em> resolved
+	by [=computed value=] time,
+	and thus will inherit as a static numeric value.
+	However, if the argument [=calculations=] aren't resolved
+	until [=used value=] time
+	(such as if they include <<percentage>> values
+	that require layout information to resolve),
+	[=inheritance=] will transfer the ''random()'' function itself.
+	(This is no different, however, to the behavior of the <<percentage>>s themselves,
+	which would inherit as <<percentage>>s
+	and thus might resolve to different values on the child elements.)
+
 
 	Issue: At least in theory it should be fine to use ''random()''
 	in non-property contexts,