code line numbers disappeared

[cscheid]

repro

---
title: "Untitled"
format: html
---


```{r}
#| code-line-numbers: true

1 + 1
```

[mcanouil]

It does not affect revealjs and pdf at least.
typst does not have line numbers but not sure it supported it in the first place.

[mcanouil]

It seems the issue appeared with the copy button fix.

• html - fix code-copy style (#5538) #12787

[mcanouil]

That's the following rule that is causing the issue:

pre.sourceCode {
  overflow-y: auto !important;
}

auto and scroll lead to the line number to "disappear" while visible reverts the copy button fix.

[cscheid]

I think we will need to make this change in order for everything to work:

We still would like to change the DOM so that the button is inside the surrounding div and not the pre element, but that goes in a separate PR.