Quiz interface bug (Introduction to React.js Part 1, JSX quiz)

I took the JSX quiz after finishing Intro to JSX and Advanced JSX and most questions displayed properly but some did not,

I would have a multiple choice question with four response options but only with the bottom three were fully visible.

I tried first in Edge and I had the same problem when I retook the test in Firefox 47.0.1: Below is a screenshot from Firefox.

Note how the vertical scrollbar is at the top, but I only see the lower part of the quiz page.