Support for the sass/scss syntax

[abichat]

With the latest version of rmarkdown, it is now possible to use the sass and scss syntax to have more intelligible and elaborate style sheets.

However, using this type of files with xaringan (0.20.2) leads to the following error:

Erreur : "theme.scss" is not a valid xaringan theme. Use `xaringan:::list_css()` to view all built-in themes.
Exécution arrêtée

It would be a great enhancement to support sass and scss syntax too :)

Thanks!

---

By filing an issue to this repo, I promise that

• I have fully read the issue guide at https://yihui.org/issue/.
• I have provided the necessary information about my issue.
  • If I'm asking a question, I have already asked it on Stack Overflow or RStudio Community, waited for at least 24 hours, and included a link to my question there.
  • If I'm filing a bug report, I have included a minimal, self-contained, and reproducible example, and have also included xfun::session_info('xaringan'). I have upgraded all my packages to their latest versions (e.g., R, RStudio, and R packages), and also tried the development version: remotes::install_github('yihui/xaringan').
  • If I have posted the same issue elsewhere, I have also mentioned it in this issue.
• I have learned the Github Markdown syntax, and formatted my issue correctly.

I understand that my issue may be closed if I don't fulfill my promises.

[cderv]

After looking into it, moon_reader() is using html_document() as base format and css argument is passed to it. So as the latter support .scss, the former should be able to benefit from that.

Currently it does not work only because a check is done: if css argument contained another thing that a filename ending with .css, it is considered as a built in theme.

xaringan/R/render.R

Line 99 in 1cca625

theme = grep('[.]css$', css, value = TRUE, invert = TRUE)

I think if we just relax this check, this would work.

We plan to latter offer better support for theming built in xaringan in other tools, but this would be only a way to benefit from new rmarkdown support for now.