Multiple background images work with Quarto + revealjs, but they do not embed into the combined HTML file with `embed-resources`.

MWE:

```{r}
---
title: "Untitled"
format: revealjs
embed-resources: true
---

## Test {background-image="image1.jpg, image2.jpg, image3.jpg, image4.jpg" background-size="50% 50%,50% 50%,50% 50%,50% 50%" background-position="top right,top left,bottom left,bottom right"}

## Local image embeds fine

![](image1.jpg)

## URL image also embeds

![](https://quarto.org/quarto.png)
```
2023-04-04T12:26:14Z
sebdunnett
closed
Multiple background images do not embed in combined HTML file
https://github.com/quarto-dev/quarto-cli/issues/5083