fix(docs): Improve fit-content and other sizing keyword pages

[dipikabh]

Description

A user on Discord reported that the description for fit-content was misleading and unclear.

I also found that the reference to fit-content(stretch) is outdated and should be removed.
From CSS Box Sizing Level 3 spec:
> Note: This section previously defined stretch and fit-content as keywords representing the stretch-fit size and fit-content size, respectively. These keywords have been deferred to Level 4 (along with an additional contain keyword that behaves similarly to stretch but preserves the preferred aspect ratio, if any) to better work out the implications in situations with indefinite available space.

Updates in this PR

• Improved and clarified the description of fit-content.
  • Removed the outdated reference to fit-content(stretch). Updated the note.
  • Moved the formula to the "Description" section.
• Made the language and structure more consistent across other related sizing keyword pages: max-content and min-content.
• Made light edits to the related glossary page for Intrinsic size.
  • Converted the subsection on "Extrinsic size" into a new glossary entry.

Motivation

To ensure content is accurate, up-to-date, and easier to understand

[github-actions]

Preview URLs (7 pages)

• /en-US/docs/Glossary/Extrinsic_size
• /en-US/docs/Glossary/Intrinsic_Size
• /en-US/docs/Web/CSS/CSS_box_sizing/Understanding_aspect-ratio
• /en-US/docs/Web/CSS/CSS_box_sizing
• /en-US/docs/Web/CSS/fit-content
• /en-US/docs/Web/CSS/max-content
• /en-US/docs/Web/CSS/min-content

Flaws (5)

Note! 2 documents with no flaws that don't need to be listed. 🎉

URL: /en-US/docs/Glossary/Extrinsic_size
Title: Extrinsic size
Flaw count: 1

• broken_links:
  • /en-US/docs/Web/CSS/Containing_block is a redirect

---

URL: /en-US/docs/Web/CSS/CSS_box_sizing/Understanding_aspect-ratio
Title: Understanding and setting aspect ratios
Flaw count: 1

• macros:
  • Macro produces link /en-US/docs/Learn_web_development/Core/Styling_basics/Cool-looking_box which is a redirect

---

URL: /en-US/docs/Web/CSS/fit-content
Title: fit-content
Flaw count: 1

• macros:
  • Macro produces link /en-US/docs/Learn_web_development/Core/Styling_basics/Cool-looking_box which is a redirect

---

URL: /en-US/docs/Web/CSS/max-content
Title: max-content
Flaw count: 1

• macros:
  • Macro produces link /en-US/docs/Learn_web_development/Core/Styling_basics/Cool-looking_box which is a redirect

---

URL: /en-US/docs/Web/CSS/min-content
Title: min-content
Flaw count: 1

• macros:
  • Macro produces link /en-US/docs/Learn_web_development/Core/Styling_basics/Cool-looking_box which is a redirect

External URLs (1)

URL: /en-US/docs/Glossary/Extrinsic_size
Title: Extrinsic size

• https://drafts.csswg.org/css-sizing-3/ (1 time) (Note! This may be a new URL 👀)

(comment last updated: 2025-08-26 14:33:58)

[github-actions]

This pull request has merge conflicts that must be resolved before it can be merged.

[github-actions]

This pull request has merge conflicts that must be resolved before it can be merged.

[estelle]

Suggested change

	- Related glossary terms:
	- {{glossary("Extrinsic size")}}
	- {{glossary("Extrinsic size")}}

we're in glossary, so don't need to include the introductory text in this section

[dipikabh]

We added this introductory label to all glossary entries some time back (per #34454, and in PRs like #34454 and #35246)

[estelle]

I only see #34451. Was there a discussion anywhere? For other sections, I could concede to prefacing multiple terms with "Glossary terms:". However, I would have voiced opposition to this choice for this section in this format due to redundancy. We're in the "glossary", glossaries define "terms"., and the See also section should only contain "related" content, including related terms..

[dipikabh]

Thanks, I see what you're saying, especially about the word "related", which could seem redundant. But also, to me "Related glossary terms:" has a different ring to it than just "Glossary terms:".

The intent to add the label in the first place was to distinguish glossary term links from other links in "See also", such as those for properties and module pages.

[dipikabh]

Hi @estelle, when you have some time, could you review this PR? Thank you!

[estelle]

@estelle

[estelle]

still working on it, but committing what i have

[estelle]

I only see #34451. Was there a discussion anywhere? For other sections, I could concede to prefacing multiple terms with "Glossary terms:". However, I would have voiced opposition to this choice for this section in this format due to redundancy. We're in the "glossary", glossaries define "terms"., and the See also section should only contain "related" content, including related terms..

[estelle]

Suggested change

	> In addition to the `fit-content` keyword, the CSS Box Sizing specification also defines the {{cssxref("fit-content_function", "fit-content()")}} function, which takes a length or percentage as an argument and behaves slightly differently.
	> In addition to the `fit-content` keyword, the [CSS box sizing](/en-US/docs/Web/CSS/CSS_box_sizing) module also defines the {{cssxref("fit-content_function", "fit-content()")}} function, which takes a {{cssxref("length")}} or {{cssxref("percentage')}} as an argument and behaves slightly differently.

[estelle]

do they serve the same purpose?

[estelle]

I dont think i understand this feature well enough to review this PR

[estelle]

do they serve the same purpose?

[estelle]

three more suggestions

[estelle]

Thanks! 🎉

[dipikabh]

Thanks for the review, Estelle!