Clarify container queries always use content box (fix #40306)

[Shrinivassab]

Description

Clarified that all container size queries measure the content box, ignoring box-sizing.

Motivation

Additional details

Related issues and pull requests

Fixes #40306

[github-actions]

Preview URLs

• /en-US/docs/Web/CSS/@container

Flaws (12)

URL: /en-US/docs/Web/CSS/@container
Title: @container
Flaw count: 12

• broken_links:
  • Can't resolve /en-US/docs/Web/CSS/block-contents
  • Can't resolve /en-US/docs/Web/CSS/size-feature
  • Can't resolve /en-US/docs/Web/CSS/scroll-state-feature
  • Can't resolve /en-US/docs/Web/CSS/function-token
  • Can't resolve /en-US/docs/Web/CSS/any-value
  • and 7 more flaws omitted

(comment last updated: 2025-07-27 02:58:56)

[estelle]

instead of making any of these changes, change line 130 to something like

The `<container-condition>` can include one or more boolean size queries, each within a set of parentheses. A size query includes a size descriptor, a value, and — depending on the descriptor — a comparison operator. The queries always measures the [content box](/en-US/docs/Web/CSS/box-edge#content-box) as the comparison. The syntax for including multiple conditions is the same as for [`@media`](/en-US/docs/Web/CSS/@media) size feature queries.

only use bolding when really necessary. When all cases are the same, favor adding a single note rather than repeating text.

[Shrinivassab]

Sure. I revered the changes and added your suggestion.

[estelle]

Thanks! 🎉