I tried that in the source html file and saw no difference, even in the stylesheet that ebook-convert generated. The class for the <pre> was unchanged.
I then unzipped the .epub file and hand edited the article_0/index.html file and replaced:
Code:
<pre class="calibre7">
with
Code:
<pre style="font-family: monospace">
and then re-zipped. It definitely changed the font, but didn't solve the alignment problem, so that alone won't fix it.
Really appreciate you response, as ever.