Subtitles are not working as expected

[benlandg]

Hi, I am using asciidoctor-web-pdf-win-v1.0.0-alpha.16

When publishing a pdf I can't get subititle partitioning working e.g. = Main title: Subtitle. Both main title and subtitle seem to be on the same line and "level". On the same file the subtitle partitioning works for me using regular asciidoctor

[ggrossetie]

Are you referring to the default built-in converter?
If so, we can take inspiration from the semantic converter in Asciidoctor:

https:/asciidoctor/asciidoctor/blob/cc337727cfb1479cb2d684f3de5aa38e4ab29ec5/lib/asciidoctor/converter/semantic_html5.rb#L247-L253

And update the built-in converter:

asciidoctor-web-pdf/lib/document/document-converter.js

Line 495 in 3fe542a

<h1>${node.getDocumentTitle()}</h1>