Math namespace in HTML

TIL: HTML partially supports math:

<math>
  <mrow>
    <mi>a</mi>
    <mo>=</mo>
    <mfrac>
      <mrow>
        <mo>-</mo>
        <mi>b</mi>
        <mo>±</mo>
        <msqrt>
          <msup><mi>b</mi><mn>2</mn></msup>
          <mo>-</mo>
          <mn>4</mn><mi>a</mi><mi>c</mi>
        </msqrt>
      </mrow>
      <mrow><mn>2</mn><mi>a</mi></mrow>
    </mfrac>
  </mrow>
</math>

^ It’s a valid HTML code. It renders this way:

No 3rd party libs needed.