CSS example in action

I suspect most people don't see the commit logs, so I thought I'd share a
link Brian had in his commit to a codepen that shows a working example of
his CSS example <https://codepen.io/bkardell/pen/xxLKOxo?editors=1111>in
the gap analysis <https://w3c.github.io/mathml-docs/gap-analysis/#css>.

Basically, the JS takes the "CSS" and adds aria-label so that
<mathml>
  <mrow data-intent="point"">
    <mo>(</mo>
    <mi class="arg1">0</mi>
    <mo>,</mo>
    <mi class="arg2">5</mi>
    <mo>)</mo>
  </mrow>
</mathml>

becomes
<mathml>
  <mrow data-intent="point" aria-label="the point 0 comma 5">
    <mo>(</mo>
    <mi class="arg1">0</mi>
    <mo>,</mo>
    <mi class="arg2">5</mi>
    <mo>)</mo>
  </mrow>
</mathml>