adding a stylesheet to the documentation, and a local override XSL sheet

manual/docbook/Makefile

-XSLSTYLE=/usr/share/sgml/docbook/xsl-stylesheets-1.70.1/xhtml/docbook.xsl
+XSLSTYLE=doctrine.xsl
 %.html:  %.xml
 	xsltproc  --output  $@  $(XSLSTYLE)  $<
 

manual/docbook/doctrine.css

+body, p, td
+{
+  font-family: arial, "lucida console", sans-serif
+}

manual/docbook/doctrine.xsl

+<?xml version='1.0'?>
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
+<xsl:import href="/usr/share/sgml/docbook/xsl-stylesheets-1.70.1/xhtml/docbook.xsl"/>
+<xsl:param name="html.stylesheet" select="'doctrine.css'"/>
+</xsl:stylesheet>