[css-color-4] Bring prose for HSL into line with the grammar

Author: svgeesus

css-color-4/Overview.bs

@@ -2070,10 +2070,10 @@ HSL Colors: ''hsl()'' and ''hsla()'' functions</h2>
 	''240deg'' represents sRGB primary blue, etc.
 
 	The next two arguments are the saturation and lightness, respectively.
-	For saturation, ''100%'' is a fully-saturated, bright color,
-	and ''0%'' is a fully-unsaturated gray.
-	For lightness, ''50%'' represents the "normal" color,
-	while ''100%'' is white and ''0%'' is black.
+	For saturation, ''100%'' or ''100'' is a fully-saturated, bright color,
+	and ''0%'' or ''0'' is a fully-unsaturated gray.
+	For lightness, ''50%'' or ''50'' represents the "normal" color,
+	while ''100%'' or ''100'' is white and ''0%''  or ''0'' is black.
 	<!--  unbounded hsl
 	If the saturation or lightness are less than ''0%''
 	or greater than ''100%'',
@@ -2087,7 +2087,7 @@ HSL Colors: ''hsl()'' and ''hsla()'' functions</h2>
 
 	HSL colors resolve to sRGB.
 
-	If the saturation of an HSL color is ''0%'',
+	If the saturation of an HSL color is ''0%'' or ''0'',
 	then the hue component is [=powerless=].
 
 	<div class='example' id="ex-hsl-primary-red">