Resources

Customizing the PDF output requires knowledge of CSS, Paged Media, and DITA. The following list provides some resources to help you:

CSS - You can find a good tutorial here: https://developer.mozilla.org/en-US/docs/Learn/CSS/Introduction_to_CSS. Also, the specification is available on the W3C (https://www.w3.org/Style/CSS/Overview.en.html) or on the MDN (https://developer.mozilla.org/en-US/docs/Web/CSS) websites.
CSS Paged Media - This is a part of the CSS specification that shows how to organize your publication in pages, how to use headers/footers, page breaks, and other page-related issues. The specification is available here: https://www.w3.org/TR/CSS2/page.html. Also, there is a set of hands-on examples in the Oxygen PDF Chemistry user guide: https://www.oxygenxml.com/doc/ug-chemistry/.
DITA - You will need a basic understanding of DITA elements, attributes, and structure. A good resource is The DITA Style Guide - Best Practices for Authors by Tony Self. It is available at: www.ditastyle.com and: https://www.oxygenxml.com/dita/styleguide/c_DITA_Authoring_Concepts.html. You can find all the details for every DITA element on OASIS website: http://docs.oasis-open.org/dita/v1.2/os/spec/DITA1.2-spec.html.
HTML5 - You will need a good knowledge of HTML5. You can find resources here: https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/HTML5
Webinars - Some helpful webinars are available on our website: https://www.oxygenxml.com/publishing_engine/videos.html?category=Webinars. They explain how to generate PDF from DITA documents using CSS, step-by-step.