(1) Does anyone know why the preformatted sections (<pre>) are limited to a width smaller than the width of the post? At all widths, it's roughly 75% of the comment's width. For mobile, this is especially bad, but I'm not sure why it's there on normal screens resolutions either.
(2) You could test different widths. Right click the preformatted section and choose "inspect element". You should have the <code> block highlighted. Move to the parent element, the <pre>. On the right, you should see a max-width with some pixel value. Try setting that to "100%" (without quotes) rather than some pixel amount. Does that work fine for you? Would you like that change? It would be great if someone could somehow test this on mobile as well, but on desktop (if I resize the browser) it seems to work well.