From discussion in https://github.com/quarto-dev/quarto-cli/discussions/4755

* `html` format support some variables for callout (https://quarto.org/docs/output-formats/html-themes.html#callouts) 
* This is because it is part of bootstrap SCSS file that we compile (
* For revealjs, this is just a `<style>` node that [we insert in header](https://github.com/quarto-dev/quarto-cli/blob/242276f1af2bce3a93560c55d7087cf98fafec6c/src/format/reveal/format-reveal.ts#L282-L284) of document (https://github.com/quarto-dev/quarto-cli/blob/main/src/resources/formats/html/styles-callout.html)

We should make that part of the default theme for revealjs, so that it is compile as a SASS theme, and variables can also be used (see https://github.com/quarto-dev/quarto-cli/discussions/4755#discussioncomment-5476737 by @EllaKaye)


cderv
2023-03-30T13:25:18Z
cderv
enhancement revealjs
v1.4
open
[Revealjs] Allow customisation of callouts similar as in HTML 
https://github.com/quarto-dev/quarto-cli/issues/5038