DOCBOOK-APPS: CSS for viewing XML directly

The Simplified DocBook XML distribution includes the files testcss.xml and
sdocbook.css.  I fleshed out the stylesheet for some of my documents.  I
also trimmed some of the inline declarations, because that's the default.

It looks okay in Netscape 6 Preview Release 1 and Mozilla M16.  IE 5
appears not to recognize "white-space: pre," so <screen> and
<programlisting> look bad.

For section numbers and cross-references, I need to generate text, which
requires CSS 2.  Neither Netscape nor IE seem to do that.

I'm accustomed to using character entities like &eacute; for the accented
"e" in "Cache" (the company's flagship product).  Since XML specifies
Unicode, I suppose I should switch to &#233;.