How to create a PDF document from ASDoc output (or JavaDoc, PHPDoc)?

You might try htmldoc with something like:

htmldoc-1.9 --format pdf14 --webpage --size a4 --title --no-duplex --pagemode outlines --embedfonts --textfont helvetica --fontsize 10 --outfile output.pdf package-detail.html class1.html class2.html class3.html ...

However, this currently leads to most parts being invisible text. This is not due to any ASDoc stylesheet (or the errors that happen when htmldoc reads them), as it also happens without any stylesheets.