[WillAdams]

A good example of this is Bertrand Russell's _Introduction to Mathematical Philosophy_:

https://courses.umass.edu/klement/imp/

which is available in a number of sizes _and_ has the LaTeX source available showing how the various sizes are arrived at.

[jxy]

The HTML version is quite nice. Do you know how they did the LaTeX to html conversion?

[WillAdams]

No idea. Ask the folks who manage that page?

[xigoi]

It’s still just a few different sizes. A HTML website has to support every possible width.

[WillAdams]

The LaTeX source may be easily edited to impart any size/proportion desired --- not quite as straight-forward as re-sizing a browser window, but the same ultimate effect.