revealjs chalkboard bug on safari

[cscheid]

Repro:

---
title: Chalkboard bug
format:
  revealjs:
    chalkboard: true
---

Open this document on Safari 16.6 (and presumably lower) and you see this:

Notably, this is resolved if users upgrade to macOS Sequoia (!?)

[cscheid]

The bug happens because somehow we have a .reveal > .overlay element active on safari, which has the following style:

https://github.com/quarto-dev/quarto-cli/blob/main/src/resources/formats/revealjs/reveal/css/reveal.scss#L1446-L1456

The blur itself comes from upstream:

https://github.com/hakimel/reveal.js/blob/5.1.0/css/reveal.scss#L1446-L1456

[cscheid]

It's a chalkboard bug: rajgoel/reveal.js-plugins#179

[cscheid]

I see rajgoel/reveal.js-plugins#180, but it doesn't look like it really fixed the issue on Safari for us, @cderv

[cderv]

😞 It is a bad upstream bug - you found the right link. I used the patched version already
dcd1724 (#10361) - that is really annoying it does not work for safari (I also can't test it on windows I think... 🤔 )

Did you identify in CSS inspector why the rule is not applying ?

If we can identify we can patch our version and report upstream.

[cscheid]

The rule at play is .reveal > .overlay, but if you look at it, that rule clearly has an intentional blur() filter. I suspect what's happening is that something in Safari is going wrong and the div should not be visible.