Not possible to navigate to headings inside non-open details elements (in markdown documents)

[Malvoz]

🏷️ Discussion Type

Bug

💬 Feature/Topic Area

Markdown

Body

Given the following content in a README.md in a repository:

# Heading level 1

## Heading level 2

<details>
  
### Heading level 3

</details>

produces the outline:

Clicking "Heading Level 3" in the outline sidebar does not expand the <details> element to show the user the Heading level 3.

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[queenofcorgis]

Hi @Malvoz 👋🏼

Thanks for posting in our community. We took a look into this and it looks like this is the result of combining HTML and Markdown.

Proper formatting would be to get your intended result:

<details><summary><h3>Heading</h3></summary>
content
</details>

[Malvoz]

Thanks for the response @queenofcorgis. The example I provided was rather simplified, I have a section with many headings in a details element, something along the lines of:

# Heading level 1
content

## Heading level 2
content

<details>
<summary>My details</summary>
  
### Heading level 3
content

#### Heading level 4
content

### Heading level 3
content

#### Heading level 4
content

</details>

## Heading level 2
content

Using a separate <details> element for each level 3 and level 4 heading (for example) isn't quite suitable in my case.

(Notably, if I do a browser find-in-page search for any of the content inside the details element(s) they do open, per whatwg/html#6466.)

Anyhow, I've gotten used to the fact that I'm not able to access those details very quickly. I don't feel strongly about it, but it's certainly a bit of a usability issue, and a bit disorienting the fact that when I do click a heading in the Outline sidebar the page scrolls but because the <details> does not open the browser scrolls to irrelevant content.

[Malvoz]

FWIW, I tested the following HTML in a standalone document directly in the browser (outside of Github that is):

<h1>Heading level 1</h1>

<a href="#h2">Go to h2</a>

<details>
<h2 id="h2">Heading level 2</h2>
</details>

If I add #h2 to the browser URL alternatively click the "Go to h2" link: in both cases the <details> element is opened, a browser functionality that is seemingly suppressed when navigating inside Github markdown documents.