OK, it looks like CloudFlare DOES pass along the content-type. (Sorry, CloudFlare. You're even better than I realized!)

I think it'd still be helpful to include the content-type in the HTML, nevertheless.

Maybe it does. I'll have to run some further tests and get back to you on this.

(So far, though, I've had to disable CloudFlare's cacheing to get the pages to display correctly.)