I have stylesheets containing instructions to display page numbers using, for instance, the following:

@top-left-corner {text-align:left;vertical-align:bottom;margin-left:1cm;content:counter(page)}

Is it possible to display, along with the number, the total number of pages, e.g. 1 of 20, 2 of 20 etc.? If so, how would I do this?

The "pages" counter holds the total number of pages in the document:

content: counter(page) " of " counter(pages)