darcy2

Thanks, Hristo, for the quick and effective support. I switched off the CSS combination and minification front end options. Also javascript options. Problem solved.

Hi Brian. As far as I can tell, it happened whenever I used firefox – version 16.0.2 with foxlingo 2.7.8.
The code that got inserted into posts is the script that I quoted at the top of this discussion. You won’t see it in the post now because I’ve deleted it. The “hash” that’s concerning me is not in the post but in the URL: the #.UNLEQI1FDDc bit at the end of the post’s web address, and I don’t know how it got there, what it means or how to get rid of it.
In answer to your question (files v database), WordPress generates posts from a database, as I understand it.
Thanks for your investigations and any further enlightenment.

I’ve just got a new computer, but yes I did have Foxlingo as a Firefox extension on the old one and I was using Firefox as my main browser.

Thanks for the suggestion, which I tried. No joy. The weird thing is that whatever changes I make to style.css, it has no effect – even after reactivating the theme.
To clarify, it’s the content background I’m trying to change i.e. the colour behind the text, not the colour behind the page.

That works. However, “Read the Rest of this entry” now comes after all posts/exerpts, including short ones that don’t have anything more to read. Is there a way to make this solution apply only to longer posts? Or maybe add the link manually to individual posts?

Thanks for the very clear explanation. I see the issue now. I can only have all the ‘read more’ links at the cost of increasing duplicate content.
Is there another way to add a link at the end of each exerpt, linking back to the full post – not to duplicate content?
If not, then, yes, I’d be grateful for the code you suggested, when you have time.
Thanks again.