Nested <details> have a gap at the bottom

[ThePotatoArchivist]

Please confirm the following.

• I checked the existing issues for duplicate problems
• I have tried resolving the issue using the support portal

What browsers are you seeing the problem on?

No response

Describe the bug

If you put a <details> inside a <details>, when the outer is expanded the inner will display a gap at the bottom.

Steps to reproduce

1. In some markdown field, enter

<details>

<summary>Test</summary>

<details>

<summary>Test</summary>

Content
  
</details>
  
</details>

2. Show preview
3. Expand the outer details
4. The inner details has a gap at the bottom as if it were open

Expected behavior

It should not display a gap, like top-level <details>.

Additional context

I skipped the support portal step because I assume this isn't a support thing