[css-fonts-4] dark mode palette example

Author: svgeesus

css-fonts-4/Overview.bs

@@ -5628,6 +5628,14 @@ Animation type: discrete
 
 </dl>
 
+<div class="example">When dark mode is in effect, use a dark mode palette
+	<pre>@media (prefers-color-scheme: dark) {
+		.banner {font-palette: dark;
+		}
+	}
+	</pre>
+</div>
+
 <div class="example">When color is not supported at all, select the monochrome glyphs rather than rendering the colored glyphs in monochrome:
 	<pre>@media not (color) {
 		font-palette: none;