The sidebar had a fixed 230px, which is absolutely untenable if your
phone has 700px in total and we only use 85% of that.
So this moves the sidebar to the bottom for now, which isn't *great*,
but at least it leaves the text readable and allows navigating the ToC.
One of these days I'll understand what the heck CSS is.
[ci skip]
Released under the Python Software Foundation License, this one
doesn't look awful (no green top bar, huzzah!).
Lightly forked it to remove the donation footer (we don't take any)
and to change the python references to fish references.
The image is just our favicon, which is a stylized "f" and therefore
not fantastic (are we facebook?), but it's the best I found, and the
thing before had no images at all.
Fixes#6500
(as far as I'm concerned)
