describe hwb in pseudo code

Author: romainmenke

css-color-4/Overview.bs

@@ -1296,7 +1296,16 @@ will have a [=powerless=] hue component.
 	When changing a powerless hue component to a [=missing component=],
 	the chroma (or other measure of colorfulness, such as saturation in ''hsl''; see [=analogous components=]) is set to zero
 	to avoid amplifying floating-point noise.
-	In the case of ''hwb'' set ''b'' to ''100 - w'' or if either ''b'' or ''w'' is missing set the other component to ''100''.
+	For ''hwb'' follow these steps instead:
+		<pre>
+		1. if W + B is greater than 99.999 and W + B is less than 100
+		2. if W and B are not missing
+			2.1. set B to 100 - W
+		3. else if W is not missing
+			3.1. set W to 100
+		4. else if B is not missing
+			4.1. set B to 100
+		</pre>
 
 <h3 id=parse-color>
 Parsing a <<color>> Value</h3>