w3c
diff --git a/‎css-color-5/Overview.bs‎
Lines changed: 19 additions & 8 deletions b/‎css-color-5/Overview.bs‎
Lines changed: 19 additions & 8 deletions
@@ -223,17 +223,14 @@ Mixing Colors: the ''color-mix()'' Function {#color-mix}
 		they are scaled accordingly so that they add up to 100%.
 	6. Otherwise, if both are provided and add up to less than 100%,
 		the sum is saved as an alpha multiplier.
-		They are then scaled accordingly so that they add up to 100%.
+		If the sum is greater than zero,
+		they are then scaled accordingly so that they add up to 100%.
 
 	This means that
 	<var>p1</var> becomes <var>p1</var> / (<var>p1</var> + <var>p2</var>)
 	and
 	<var>p2</var> becomes <var>p2</var> / (<var>p1</var> + <var>p2</var>).
 
-	<!-- @@ Need to handle the sum to zero case to generate transparent black
-	 	https://github.com/w3c/csswg-drafts/issues/11678#issuecomment-2686226875
-	-->
-
 <wpt>
 	color-mix-percents-01.html
 	color-mix-percents-02.html
@@ -270,18 +267,19 @@ Mixing Colors: the ''color-mix()'' Function {#color-mix}
 
 After normalizing both percentages, the result is produced via the following algorithm:
 
-1. As described in [[css-color-4#interpolation]],
+1. If the alpha multiplier is zero, the result is ''transparent'', converted to the specified interpolation <<color-space>>
+2. Otherwise, as described in [[css-color-4#interpolation]],
 	both colors are converted to the specified interpolation <<color-space>>,
 	taking into account any [=analogous components=].
-2. Colors are then interpolated in the 	specified color space,
+3. Colors are then interpolated in the 	specified color space,
 	as described in [[css-color-4#interpolation]].
 	If the specified color space is a ''cylindrical-polar-color'' space,
 	then the <<hue-interpolation-method>> controls the
 	interpolation of hue, as described in
 	[[css-color-4#hue-interpolation]].
 	If no <<hue-interpolation-method>> is specified, it is as if
 	''shorter'' had been specified.
-3. If an alpha multiplier was produced during percentage normalization,
+4. If an alpha multiplier was produced during percentage normalization,
 	the alpha component of the interpolated result is multiplied
 	by the alpha multiplier.
 
@@ -298,6 +296,10 @@ After normalizing both percentages, the result is produced via the following alg
 	/html/canvas/element/fill-and-stroke-styles/2d.strokeStyle.colormix.html
 </wpt>
 
+	<!-- @@ Need WPT to test the sum to zero case, to generate transparent black
+	 	https://github.com/w3c/csswg-drafts/issues/11678#issuecomment-2686226875
+	-->
+
 The result of mixing is the color at the specified percentage along the progression
 of the second color to the first color.
 
@@ -387,6 +389,15 @@ and a percentage of 100% returns the same color converted to the specified color
 		* which is a slightly-blueish green: <span class="swatch" style="--color: rgb(7.7377% 52.5730% 37.3213%)"></span>  rgb(7.7377% 52.5730% 37.3213%)
 </div>
 
+<div class="example" id="ex-mix-zero-sum">
+	In this example, both percentages are zero, so their sum is also zero:
+
+	<pre class="lang-css">color-mix(in oklch, teal 0%, olive 0%);</pre>
+
+	Thus, the result is transparent black, in the ''oklch'' color space:<br>
+	<span class="swatch" style="--color: transparent"></span> oklch(0% 0 none / 0)
+</div>
+
 <h3 id="color-mix-color-space-effect">
 	Effect of Mixing Color Space on color-mix
 </h3>