[css-anchor-position-1] Correct use of part-like pseudo-element

Author: fantasai

css-anchor-position-1/Overview.bs

@@ -406,7 +406,7 @@ in anchor positioning.
 	if all of the following are true:
 
 	* |possible anchor| is either an [=element=]
-		or a [=part-like pseudo-element=].
+		or a fully styleable [=tree-abiding pseudo-element=].
 
 	* |possible anchor| is in scope for |positioned el|,
 		per the effects of 'anchor-scope' on |positioned el|