While I recognize that any mimicry of Tufte's print approach in CSS is going to come across as prescriptivism, that was not the point. Tufte CSS was a toy project that seemed worth sharing. It turns out, figuring out which of his methods translate from print to the web is not straightforward. It's an exercise. That process of implementing sidenotes (for instance), and thinking about what they mean in the modern web, is valuable. Sidenotes are but one technique, like data-"ink" ratios and minimal use of hierarchical headings are merely guiding ideas. My goal with Tufte CSS was not to say "this is how websites should look" but rather "here are some techniques we've found useful elsewhere; maybe you'll find them useful on the web" and "here is a sketch of implementing this set of ideas".

While I do think Tufte CSS could be a good starting point for a variety of webpages that want to communicate a point using text, tabular data, figures, and code, I don't think that websites should see Tufte CSS, or Tufte's print projects in general, as a design goal. Different projects, in whatever media, should present their information as best suits their particular circumstances.

Anyway, I apologize for giving the impression of cargo-culting. If there's any way I can change the wording in either the README or the demo doc to better reflect that this is not a design prescription, please let me know.