[css-fonts-4] Clarify language about font-weight acceptible range

Author: litherum

css-fonts-4/Overview.bs

@@ -302,7 +302,7 @@ other.</p>
 		<dt id="font-weight-numeric-values"><dfn><<number>></dfn></dt>
 		<dd>
 			These values form an ordered sequence, where each number indicates a weight that is
-at least as dark as its predecessor. Only values between 1 - 999 are valid, and all other values are treated as parse errors. Certain numeric values correspond to the commonly used weight names below (Note that a font may internally provide its own mappings, but those mappings within the font are disregarded):
+at least as dark as its predecessor. Only values greater than 0 and less than 1000 are valid, and all other values are treated as parse errors. Certain numeric values correspond to the commonly used weight names below (Note that a font may internally provide its own mappings, but those mappings within the font are disregarded):
 
 			<ul>
 			<li>100 - Thin</li>