@anon12638239: how dare you interject like that ??!! 
I am just joking !! This is a public forum so anyone can jump into a thread at any time, that’s the beauty of it.
What’s more, I am very grateful to you because it was indeed that little “s” that was the “bug”. I am amazed and impressed you picked it up !!
So, many thanks for “interjecting”, it was a most fruitful contribution, and I want to thank you for it because I was disappointed to have to drop this.
I also want to thank @Moonbase59 for sharing this elegant snippet with us all, AND for his patience with a CSS oaf like me. I am ashamed to have made such a basic mistake that is only due to sloppiness - my sincere apologies!