The usual way to convert a bookdown to PDF relies on LaTeX.
In order to customize the rendered document, one has to pass the painful LaTeX learning curve.
However, there is an underrated way to produce a PDF with HTML and CSS only.
This template was developed in order to introduce this alternative.
Here are two screenshots.
The main feature of this template is that the layout is done using CSS. It relies on the
bookdown::html_document2 default format.
Since browsers do not support the CSS features needed to build a PDF, the PDF file is rendered using a dedicated converter (Prince XML software, www.princexml.com).
In order to facilitate the use of HTML/CSS to PDF converters, a package was developped (see here).
You can find some instructions to build the book in the PDF file.