The light is shining brightly! I am embarrassed to reveal the total amount of time I have spent on this issue (hint - measured in days), but in just a few minutes my problem is solved and I have learned an invaluable troubleshooting technique.
The trouble, revealed in the page source, was glaringly obvious. As several contributors pointed out but Old Pedant broke out the most clearly, my use of single and double quotation marks was the culprit. How many times I have repeated this error......
I am in the process of digesting the rest of the corrections, suggestions, and remarks, but for now my heartfelt thanks to all who contributed!!