Hi,
Current debian-reference and maint-guide build from docbook-xml has CSS.
They can be used here. Since chaper jumping is a bit different, that
may need adjusted.
Add
<link rel="stylesheet" type="text/css" href="debian.css"/>
right after <title> ... </title> at the top of file in <head> section.
Place attached CSS and have images in the right location if you wish to
use it.
Since div is not used in html generated by debiandoc-sgml, it is not
optimal but use of this CSS make it look similar to docbook-xml
generated Debian pages :-)
Osamu