Thank you for all your help and advice guys.
It's helped a lot.
Let me explain the history of my CSS.
The CSS was given to me by a friend :
I'd decided how I wanted every book to appear (I don't read technical stuff with precise formatting) and set up my reader accordingly, but had found too many ebooks imposing on me fonts, sizes and spacings I didn't like, or even font sizes that were too small for me to read. No idea why they do this, when all I want is the words.
Anyway, I found that in most cases, deleting the stylesheets in Calibre did the job, so I started doing that. (I stopped writing programs in the 70s and didn't really want to start again if I could avoid it)
My friend suggested that it might be better to replace the stylesheet with a simple standard one to give the desired result, and kindly gave me that one.
I've used it since then with no ill effects and was grateful to have it.
The appearance of those particular headings in grey (blue on a color monitor) was a very minor irritant, that I thought might be cured by amendments to that CSS.
I checked and as you've pointed out, the book for some reason uses links for those headings, so now I know what's going on there too.
Thanks again, your advice is much appreciated
