Almost no extra work at all. You can see the full transcript here: https://gist.github.com/simonw/9d7cbe02d448812f48070e7de13a5... - it really was just those two prompts, then I copied the result out into a document to test it.

I modified the HTML a tiny bit before publishing it - I set the font to Helvetica and added the note at the bottom of the page showing the prompt I used.

The whole project took less than 5 minutes - then another 10 to write it up.

That's incredible.