[css-values] measurement -> quantity

Author: fantasai

css-values/Overview.bs

@@ -662,13 +662,14 @@ Percentages: the <<percentage>> type</h3>
 	It corresponds to the <<percentage-token>> production
 	in the <a href="https://www.w3.org/TR/css-syntax/">CSS Syntax Module</a> [[!CSS3SYN]].
 
-	Percentage values are always relative to another measurement,
+	Percentage values are always relative to another quantity,
 	for example a length.
-	Each property that allows percentages also defines the measurement to which the percentage refers.
-	This measurement can be a value of another property for the same element,
-	that of a property for an ancestor element,
-	or a measurement of the formatting context
-	(e.g., the width of a <a>containing block</a>).
+	Each property that allows percentages also defines the quantity to which the percentage refers.
+	This quantity can be a value of another property for the same element,
+	the value of a property for an ancestor element,
+	a measurement of the formatting context
+	(e.g., the width of a <a>containing block</a>),
+	or something else.
 
 	In cases where a <<percentage>> can represent the same quantity
 	as a <a>dimension</a> or <a>number</a> in the same <a>component value</a> position,