smart quotes in code text

Some pages like https://graphviz.org/docs/attrs/diredgeconstraints/ show smart quotes when listing code snippets:

This impedes copy-pasting code because the pasted version does not parse. I think we should be avoiding smart quotes in code. Some other pages like https://graphviz.org/docs/attrs/ratio/ get this right:

So apparently it is possible to suppress smart quotes somehow.