Thank you for your quick reply.
So, for page breaks at the beginning of chapters, I should use the split option? This will split the file into small files. I didn't think this was what I wanted to do, as I wanted a page break, not a separate file.
However, do you think I would be better off splitting the file like this?
Also, should I remove that CSS command? I only mention it because when I googled this issue about page breaks, that was the solution that came up (it was in my original html file anyway).