I have now completely redone the blog template and CSS, and although it frightened me at first after I republished by claiming to be unable to access the site, things now seem to be working OK, more or less. The layout problems I was experiencing were largely due to incompatible expectations by the template and my own entries, which I have managed to synchronize better now. I doubt if I will ever get the results to validate with all the stuff that gets added automatically, but at least it lays out as intended.
I'm sure I could do better if I took the trouble to read the instructions, and maybe I will even do that at some point.
Hmm…once again I am experiencing the problem that when the text box for entering the content starts to scroll, I can no longer see the Post and Publish buttons. Could this be another Mozilla bug?