Try adding aria roles to one of the MathML expressions.

Author: shans

index.html

@@ -2383,7 +2383,8 @@ <h2>Calculating the length between two property values</h2>
             <dd>
               length is defined as the result of evaluating the following
               expression
-              <math display="block">
+              <div role="math" aria-describedby="math-color-length">
+              <math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
               <mrow>
                 <msqrt>
                   <msup>
@@ -2418,6 +2419,8 @@ <h2>Calculating the length between two property values</h2>
                 </msqrt>
               </mrow>
               </math>
+              <pre id="math-color-length">sqrt((ra - rb)^2 + (ga - gb)^2 + (ba - bb)^2 + 255*255*(aa - ab)^2)</pre>
+              </div>
               <p>
                 where the colors between which the length is to be measured are
                 <code>rgba(ra, ga, ba, aa)</code> and