General

PDF is a completely different technology than for example HTML. Thus to produce quality PDF documents, use LaTeX or other applications. HTML is not well suited for PDF creation.

Converting from (X)HTML + CSS

Converting an HTML document to a PDF one is not easy. HTML should not be chosen as a view technology if you need to output to a PDF or print your document. However, various libraries still exist to convert an HTML document to PDF.

Be sure to choose a large font size in your HTML document. I set a base font-size on the body equal to 20px. Use relative font-sizes in your XHTML document (eg, font-size: 0.85em;).

This PHP library (coming from a Perl port) is excellent. It can convert remarkably well XHTML documents with CSS properties. However, it has the following caveats:
- Make sure your CSS is perfectly valid. Sometimes you will need to specify a clear property explicitely. With a bit of effort, your output document will be very close to the original Firefox rendering.
- Be careful with images. html2pdf does not support transparency. You should also use high quality (very large) images in your HTML document, giving its actual size via the CSS properties.
- You can use either the FPDF or PDFLIB libraries to output to PDF. I tried both but did not see any noticeable differences (although the pdflib package must be installed separately in Gentoo).