[css-color-hdr] Added example color-mix() with three colors

Author: svgeesus

css-color-5/Overview.bs

@@ -438,6 +438,23 @@ Otherwise, use the specified colorspace for mixing.
 	<span class="swatch" style="--color: transparent"></span> oklch(0% 0 none / 0)
 </div>
 
+<div class="example" id="ex-mix-three-no-percents">
+	In this example three colors are mixed, 
+	and no percentages are given 
+	so each color contributes one-third of the final result.
+
+	<pre class="lang-css">color-mix(in oklab, teal, olive, blue);</pre>
+
+	The calculation is as follows:
+	* <span class="swatch" style="--color: teal"></span> teal (#008080) is oklab(54.31% -0.0896 -0.0236)
+	* <span class="swatch" style="--color: olive"></span>  olive (#808000) is oklab(58.07% -0.0428 0.1191)
+	* <span class="swatch" style="--color: blue"></span>  blue (#0000FF) is oklab(45.20% -0.0325 -0.3115)
+	* mixed lightness is (54.31 + 58.07 + 45.20) / 3 = 52.53%
+	* mixed a is (-0.0896 + -0.0428 + -0.0325) / 3 = -0.0550
+	* mixed b is (-0.0236 + 0.1191 + -0.3115) / 3 = -0.0720
+	* mixed result is <span class="swatch" style="--color: rgb(15.62% 45.07% 58.8%)"></span> oklab(52.53% -0.0550 -0.0720)
+</div>
+
 <h3 id="color-mix-color-space-effect">
 	Effect of Mixing Color Space on color-mix
 </h3>
@@ -3706,7 +3723,7 @@ This specification adds a way to ensure adequate contrast for text whose backgro
 </h3>
 
 <ul>
-	<li><i>none</i></li>
+	<li>Added a color-mix() example with three colors, now that it is no longer restricted to just two.</li>
 </ul>
 
 <h3 id="changes-20250318">