Migrating from XSLT stylesheets to CSS themes

[CharlesDM]

Our organization currently uses XSLT stylesheets for transformations, and I've been tasked with spearheading the process of creating CSS stylesheets for use with the new DITA OT 4.3 themes. I kind of understand CSS...a bit...and I get the way these themes work and cascade off one another, but I don't really understand what's happening at the backend of OxygenXML or how these XSLT stylesheets are structured. How important is it that I understand XSLT before trying to convert our current stylesheets to CSS, and does anybody have some hot tips they want to share on how to make the XSLT-to-CSS migration a less painful experience?

[julien_lacour]

Hello,

By migration do you mean going from DITA Map PDF - based on XSL-FO to DITA Map PDF - based on HTML5 & CSS in order to generate PDFs using CSS instead of XSLT stylesheets?
DITA OT 4.3 themes you mentioned aren't based on CSS but on YAML, for more information you can check DITA-OT specs.

Regards,
Julien