::part() documentation gives the false impression that :last-child and friends are usable on shadow parts

[DavidJCobb]

MDN URL

https://developer.mozilla.org/en-US/docs/Web/CSS/::part

What specific section or headline is this issue about?

Description

What information was incorrect, unhelpful, or incomplete?

Emphasis mine:

Pseudo-classes (such as ::part(label):hover) can be appended to the ::part() selector, but structural pseudo-classes that match based on tree information (such as :empty), rather than local element information (such as :last-child), cannot be appended.

The :last-child pseudo-class is a tree-structural pseudo-class and therefore cannot be used on ::part(...). To clarify, foo:last-child::part(name) works, but foo::part(name):last-child does not.

What did you expect to see?

There should not have been a parenthetical after "local element information," much less an inaccurate one. The start of the sentence already gives an example of a selector based on local element information (:hover) being usable on a shadow part.

Do you have any supporting links, references, or citations?

• The :last-child pseudo-class is listed in MDN's "tree-structural pseudo-classes" section.
• The :last-child pseudo-class belongs to the tree-structural pseudo-classes category in Selectors Level 4.

Do you have anything more you want to share?

No response

MDN metadata

Page report details

• Folder: en-us/web/css/_doublecolon_part
• MDN URL: https://developer.mozilla.org/en-US/docs/Web/CSS/::part
• GitHub URL: https://github.com/mdn/content/blob/main/files/en-us/web/css/_doublecolon_part/index.md
• Last commit: 4d51a21
• Document last modified: 2025-02-05T17:09:05.000Z