Making html documents less self-contained

In a separate issue https://github.com/AlexsLemonade/refinebio-examples/pull/303#issuecomment-714528242, I floated the idea of making the html documents not-self contained to reduce download times and make the html a bit cleaner to look at.

I made some attempts in https://github.com/AlexsLemonade/refinebio-examples/tree/jashapiro/non-standalone, but I don't think they are ready to go.

The main issue is that using this feature requires that we make certain components (notably .css files) relative paths. We can do this, but it is a bit brittle at the moment.

The other issue is that this ends up including a bunch of font files in the lib directories, which are large and largely unnecessary!

So I am filing this as a record, and maybe for future thoughts, but not expecting this to be worked on for a while.

Start by reviewing the discussion in PR #303 and the non-standalone branch linked in the issue. Examine how relative CSS paths and generated lib font files affect the HTML output; the work is complete only when a concrete, maintainable approach is agreed and the resulting documents meet the intended download-size and cleanliness goals.

Written by the indexing model from the issue text.