Although there are word processors that can do much of the same formatting shown here, LATEX is freely available for many UNIX platforms and is installed on the Linux systems in the Computer Systems Lab. Another really powerful feature of this document processing language is that people have written programs that will convert a standard document written in LATEX format into a complete website using the program latex2html.  The program converts every section or subsection into a separate web page including appropriate navigation tools, and also turns all of the equations and into separate GIF images.
The software also creates a separate cascading style sheet so that the resultant document can be quickly converted to some desired format. Take a look at the cascading style modifications used to change the background to white in this document as well as headers and links to different colors: latex.css