@designsimply, you are the best! Thank you. I tried all sorts of things... never would have even considered this. Whether this would be considered a bug or not, I don't know, but it's sure frustrating when something like this happens but the fix doesn't follow any logic (that I know of anyway). In any case, again, I thank you immensely!
Now, three more CSS questions if you don't mind:
1) I would like the margins on all the one-column pages to be a little deeper (more blank space between the text and the edge of the post/page). How do I do that in CSS?
2) I would like to change the background color of the post/pages to something a little more off-white. Haven't found the right color yet, but when I do, how do I add that to the CSS?
3) How would I move the nav bar beneath the header? Not sure I want to do that permanently, but I'd like to see what it would look like.
Again, thanks in advance.