I see lines like the following at https://plotly.com/python/v3/alpha-shapes/

Let $S$ be a finite set in $\mathbb{R}^d$, $d=2,3$ (i.e. a set of 2D or 3D points).

What is it? MathML or embedded latex or something else? Do I need an extension to view it? I have already tried chrome, edge, firefox, opera on windows. I looked at the html of the page I see use of the term mathjax.