Install css2xslfo by entering the following commands in the terminal:
sudo apt update sudo apt install css2xslfo
XML+CSS2 to XSL-FO converter
CSSToXSLFO is a utility which can convert an XML document, together with a CSS2 style sheet, into an XSL-FO document, which can then be converted into PDF, PostScript, etc. with an XSL-FO-processor. It has special support for the XHTML vocabulary, because that is the most obvious language it would be used for. The tool has a number of page-related extensions. It also comes with an API in the form of an XML filter.