I would like to acknowledge Claire Tanfa who provided some very useful code tips that I used many decades ago.
She was a programmer of some skill who posted a blog called Tanfa - CSS Design, and offered her code to anyone who chose to use it.
Unfortunately, Claire has dropped off the radar and despite my many attempts to locate her on the internet I have been unsuccessful.
If you come across Claire, please let me know so that I can thank her personally.