How best expose stylistic paramters of a template?

[arthur-shaw]

If one were building a wrapper around pagedown (say, like pagedreport), how should one think about providing users access to style parameters of templates?

For example, I understand that one could have R write CSS variable definitions (e.g. here and around 16:47 here). But I'm not sure whether this is the best or only strategy avaialble.

Beyond that, what type of stylistic parameters can already be passed to pagedown::html_paged() via ... and where can one find a list of them?