Add a horizontal scrollbar to MathJax formula blocks

Question

MathJax formula blocks (i.e. $$these$$, not single-dollar-sign $inline$ mathjax) sometimes get wide, especially when they're arrays. Wide formulae don't play nicely with the responsive design though and instead overflow into the sidebar if the window is narrow enough.

Could MathJax formulae get a horizontal scrollbar?

If I add the following CSS we get this pretty scrollbar exclusively while the viewport is narrow enough like above:

.math-container {
  overflow-x: auto;
  display: block; /* or use a <div> instead of a span */
}

Then we can also scroll to see the rest of the table, and it's legible because it's not overlapping with the sidebar!