The wide page is caused by the long lines in the
<pre> blocks. We
fix this by changing all the
<pre> blocks to have class "code", if
they weren't already. Then adjust the CSS for the "code" class to add
a horizontal scrollbar if needed.
We also had to set the width of the box to 70vw. This was experimentally determined to give a reasonably wide area for the code while not making the regular text wider than the screen.