Duplicating website's formatting in local doc builds

I'm wondering how to do $SUBJECT.  The fine manual suggests

    make STYLE=website html

but what I'm getting here with that is not a very close approximation
of what I see at postgresql.org.  It's closer than the default,
but it's not the same font, margins, etc.

I also wonder why duplicating the website's style isn't the default.
Doesn't seem like having authors optimize for some other style is
what we really want.

            regards, tom lane