I don't have this particular issue, but instead the text size is hilariously huge. The CSS contains this fragment:

  @media (min-resolution: 1.5dppx) {
   :root {
    font-size: 2.4rem;
   }
  }

My 27 inch 4k monitor comes in at a device pixel ratio of ~1.58, triggering this (presumably) phone-targeted style.