Handle idprefix and idseparator in documents for synchronized scrolling

[de-jcup]

A config locking like

ifndef::env-site[]
:toc: left
:idprefix:
:idseparator: -
endif::[]

does change ID creation for asciidoctor parts and so synchronized scrolling does not work

(idprefix and idseparator ar the parts...)

So the headline id build mechansim must handle this

[yeroc]

What exactly breaks synchronized scrolling? It's not working in my documents which have the following:

= Document Title
ifdef::env-github,env-browser[:outfilesuffix: .adoc]
:sectlinks:
// number our sections
:numbered:
:toc:
:toclevels: 3
:toc-placement!:

toc::[]

[de-jcup]

This issue was about idprefix and idseparator

Both settings seems to change calculation of ids used inside output html documents.

Curret implementation has problems when id calculation is customized (in my first example it was :idseparator: -

Your given example should not have this problem, but I am not sure. Maybe its related too.