The chapter on branding could do with a section on customising brands. It should cover how to customise the CSS, as well as how to set up and override the XSL. Might also be good to give an over view of how the XSL parameters work and where to find detailed lists of DocBook XSL parameters.
HSS-QE has reviewed and declined this request. QE for this bug will be handled by IED.
The PUG is way out of date, I don't see any point it picking random sections for attention when the doc is in such a useless state.