[css-color-5] Better define serialization of relative colors whose origin color is currentColor. sRGN, hsl and hwb serialize using color(srgb ...) to enable round-tripping.

Author: svgeesus

css-color-5/Overview.bs

@@ -2863,7 +2863,68 @@ followed by ")".
 <!-- need a more complex example, and one with calc too -->
 
 The serialization of the result of a relative color function
-is the resolved value.
+depends on whether the keyword ''currentColor'' is the [=origin color=].
+If so, the result is serialized as the specified value.
+This allows the correct value to be used 
+on child elements whose ''color'' property has a different value.
+Otherwise, it
+is the resolved value, 
+which is a  <<color>>,
+as defined in [[css-color-4#serializing-color-values]].
+
+The form used
+depends on the color space of the [=origin color=]:
+
+<table class="data">
+	<tr>
+		<th>mixing color space</th>
+		<th>form</th>
+	</tr>
+	<tr>
+		<td>srgb</td>
+		<td>color(srgb r g b)</td>
+	</tr>
+	<tr>
+		<td>srgb-linear</td>
+		<td>color(srgb-linear r g b) </td>
+	</tr>
+	<tr>
+		<td>hsl</td>
+		<td>color(srgb r g b) </td>
+	</tr>
+	<tr>
+		<td>hwb</td>
+		<td>color(srgb r g b)</td>
+	</tr>
+	<tr>
+		<td>xyz-d65</td>
+		<td>color(xyz-d65 x y z)</td>
+	</tr>
+	<tr>
+		<td>xyz-d50</td>
+		<td>color(xyz-d50 x y z)</td>
+	</tr>
+	<tr>
+		<td>xyz</td>
+		<td>color(xyz-d65 x y z)</td>
+	</tr>
+	<tr>
+		<td>lab</td>
+		<td>lab(l a b)</td>
+	</tr>
+	<tr>
+		<td>lch</td>
+		<td>lch(l c h)</td>
+	</tr>
+	<tr>
+		<td>oklab</td>
+		<td>oklab(l a b)</td>
+	</tr>
+	<tr>
+		<td>oklch</td>
+		<td>oklch(l c h)</td>
+	</tr>
+</table>
 
 <wpt>