I got the
postheadprefoot
plugin to work, after some frustrating days. I actually printed out
debug info to a file to find out what was wrong. But this
message put me
straight: simply uncomment a line in the plugin to get it to work.
(In my defense, I had already identified that line as the problem, but didn’t really feel that I could change it — it was by Rael, after all.)
So now the archives live on their own page, no longer cluttering up the sidebar.
Some small CSS changes were also made, mostly to try to balance semantic markup with some sort of aesthetics.