Having searched the forum / samples / documentation I've yet to discover if this exists already; apologies if it does.

Is there CSS selector that targets only the repeated <thead> elements?

/* Pseudocode */
thead::repeated { background: red; }

I'd love to be able to highlight the repeated <thead> elements differently to show that the table is a continuation of the page before; I could see the same for <tfoot> being useful too.

Thanks guys!

No, but you can do this for table captions by using multiple <caption> elements and applying the prince-caption-page property to them.

Thanks Mike, that's worked a treat

Looking about these forums you really know your stuff, kudos!