[css-values-4] Prose clarification

Author: frivoal

css-values-4/Overview.bs

@@ -1063,7 +1063,7 @@ Font-relative lengths: the ''em'', ''ex'', ''cap'', ''ch'', ''ic'', ''rem'', ''l
 	(and additionally for the ''lh'' and ''rlh'' units in the 'line-height' property)
 	on the element they refer to,
 	these units refer to the computed font metrics of the parent element
-	(or the computed font metrics corresponding to the initial values of the 'font' property,
+	(or the computed font metrics corresponding to the initial values of the 'font' or 'line-height' properties,
 	if the element has no parent).
 	When used outside the context of an element
 	(such as in <a>media queries</a>),