Most documents need no changes: a paper or a book written for print is published as it is. A document written for the web can use the companion package reflowtex.sty. Everything in the package also compiles with ordinary LA TEX, to the closest print equivalent, so the same source still gives a PDF.
\usepackage{reflowtex}% or [boxed]
The package ships in src/latex/, and the build pipeline finds it automatically. For a PDF of the same source, put reflowtex.sty next to the document or on TEXINPUTS.
Web-only and print-only
\ifreflowtex is true only when the pipeline compiles the source. Two environments build on it: webonly, whose body appears only on the web, and printonly, whose body appears only in the PDF.
This sentence is in a webonly environment, so the PDF of this page would not have it.
\begin{webonly}This sentence is in a \texttt{webonly} environment, so the PDF
of this page would not have it.\end{webonly}\begin{printonly}And this one would be in the PDF only.\end{printonly}
The next pages show what the package offers: an accordion of panes, notes and hints, and boxed theorems. Custom kinds explains the two primitives they are all built from, and how to build your own.