Extract custom CSS in Site modules into a file

[abelsromero]

What is this issue about?

• [ ] Bug report 🪲
• [x] Feature request 🏎
• [ ] Question ❓ Consider dropping it first in the Project Chat

Description

We want to extract the custom logic we are embedding to reduce repetition. For example we now embed for Examples https://github.com/asciidoctor/asciidoctor-maven-plugin/blob/f9c8e6739bc4d9f4c9e5280aebdcf287c10adf34/asciidoctor-parser-doxia-module/src/main/java/org/asciidoctor/maven/site/parser/processors/ExampleNodeProcessor.java#L67 the styles from https://github.com/asciidoctor/asciidoctor-maven-plugin/blob/f9c8e6739bc4d9f4c9e5280aebdcf287c10adf34/asciidoctor-parser-doxia-module/src/main/java/org/asciidoctor/maven/site/parser/processors/Styles.java#L14

Environment information

• asciidoctor-maven-plugin version: ___
• asciidoctorj version: ___
• Maven, Java and OS version: ___

[abelsromero]

Asking for support, so far I could not find a simple way to modify the header https://lists.apache.org/thread/7jgcl0o8grncryrfgfmhqb5h35orvrhj