[css-color-adjust-1] Add example for color-mix() in Forced Colors mode. w3c#11097

Author: kbabbitt

css-color-adjust-1/Overview.bs

@@ -572,6 +572,23 @@ Properties Affected by Forced Colors Mode {#forced-colors-properties}
 	UAs may further tweak these <a>forced colors mode</a> heuristics
 	to provide better user experience.
 
+	<div class="example">
+		Authors may still use features such as ''color-mix()'' in [=forced colors mode=].
+		In such cases, the [=computed value=] will behave as it would normally,
+		but the [=used value=] will be overridden with an appropriate [=system color=].
+
+		<pre highlight=css>
+		.example {
+			color: color-mix(in srgb, CanvasText, Canvas);
+		}
+		</pre>
+
+		The [=computed value=] for 'color' will be a 50-50 blend of the ''CanvasText'' and ''Canvas'' [=system colors=].
+		That value will inherit to descendants and be observable via APIs such as {{Element/computedStyleMap()}}.
+
+		The [=used value=] for 'color' will be a system color chosen by the UA, for example ''CanvasText''.
+	</div>
+
 Opting Out of a Forced Color Palette: the 'forced-color-adjust' property {#forced-color-adjust-prop}
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