to answer my own question:

> hi.  i'm wondering what the reference to "style blocks" means in the
> "CSS Support" section of the manual:
> ----
> For longer style definitions, either use several ‘HTML_HEAD’ and
> ‘HTML_HEAD_EXTRA’ keywords, or use ‘<style> ... </style>’ blocks around
> them.  Both of these approaches can avoid referring to an external file.
> ----
> 
> can anyone provide enlightenment?  thanks!

i can't say what the original author meant.  but, one can do this to get
CSS into a file:
----
#+begin_export html
<style> p { margin: 10px; }</style>
#+end_export
----

below is a small patch with clarification in the manual, if deemed
appropriate.

cheers, Greg