Updates June 2023

[Programmer]

I have made a few minor updates to the tone tests. On the reinforcement questions some text appears to remind you of which tone pairs you are trying to tell apart. Also I fixed the page to always show a vertical scroll bar. This is because I noticed that on some screen resolutions when showing the answer the scroll bar was there and when showing the question it wasn't. This wasn't very easy on the eye because the appearance of the scroll bar meant that the rest of the page content kept shifting slightly to the left or right.