Improve documentation on <url> #35029 by Sacrafex · Pull Request #43292 · mdn/content

Sacrafex · 2026-02-28T03:53:06Z

Added Further clarification to the file: behavior for the <url> CSS data type as fixes for #35030

Description

Motivation

To help readers understand browser restrictions when using <url> values.

Additional details

Linked to MDN CORS guide.

Clarified differences and file: URL limitations.

Related issues and pull requests

#35030

Added Documentation Support for <url> Fixes for Issue mdn#35029 mdn#35030

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

files/en-us/web/css/reference/values/url_value/index.md

hamishwillee

Thanks @Sacrafex

I'm deferring proper rview to @estelle as I'm not as familiar with CSS as with Web APIs.

A few comments though:

Any additions like this should be before the specifications macro/section. Generally either in the top overview, or under a description heading, after the value section.
I'm not sure if this overstates the effect of CORS. Do all of these actually get blocked on the major browsers (I'm not sure they are).
Also many CSS fetches woudl be in no-cors mode - so while correct, it feels excessive.
File URL section true, but not sure if this is the rright place.

It might be that all of this should be a see also link to more general URL docs. Let's see what @estelle says.

Sacrafex · 2026-03-02T00:44:25Z

Thanks for the comments. I'll take a look once I get a chance.

Sacrafex

I've updated the Docs with working links and a more accurate description. Please let me know if I need to make fixes and another PR.

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

github-actions · 2026-03-02T18:11:40Z

Preview URLs (1 page)

/en-US/docs/Web/CSS/Reference/Values/url_value

Flaws (1)

Found an unexpected or unresolvable flaw? Please report it here.

URL: /en-US/docs/Web/CSS/Reference/Values/url_value
Title: <url>
Flaw count: 1

macros:
- Macro htmlelement produces link /en-US/docs/Web/HTML/Reference/Elements/svg which doesn't resolve

(comment last updated: 2026-03-08 22:23:21)

estelle

made several suggestions

files/en-us/web/css/reference/values/url_value/index.md

Co-authored-by: Estelle Weyl <estelle@openwebdocs.org>

files/en-us/web/css/reference/values/url_value/index.md

Clarified the URL value requirement in the documentation.

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Clarified CORS validation requirements for CSS properties using <url> values and added information about local file access issues.

Sacrafex

Updated Requested Changes. Please let me know I should update anything else.

estelle

basic syntax-like examples can go into the description section. The examples section is more for in-depth examples generally with live rendering.

files/en-us/web/css/reference/values/url_value/index.md

Co-authored-by: Estelle Weyl <estelle@openwebdocs.org>

Clarified the description of URL values and updated examples.

Sacrafex

Fixed Changes.

files/en-us/web/css/reference/values/url_value/index.md

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

files/en-us/web/css/reference/values/url_value/index.md

estelle

looks good. Thank you. Just one last suggestion on breaking up the examples in the description

estelle · 2026-03-05T09:31:05Z

@hamishwillee OK to merge?

files/en-us/web/css/reference/values/url_value/index.md

Co-authored-by: Hamish Willee <hamishwillee@gmail.com>

Sacrafex · 2026-03-06T05:02:04Z

We should be good to merge now. If there are any final tweaks you’d like, just let me know and I’d be happy to make them.

Clarified CORS requirements for certain CSS properties referencing external resources.

Sacrafex

Added Documentation on <url>
Includes examples, definitions & clarifications.

files/en-us/web/css/reference/values/url_value/index.md

hamishwillee

Thanks very much @Sacrafex, and welcome to MDN (also @estelle for the review and feedback).

Sacrafex · 2026-03-09T00:28:00Z

No problem. I'm glad to help out. I look forward to making more contributions in the future.

Improve documentation on <url> mdn#35029

ce32ae7

Added Documentation Support for <url> Fixes for Issue mdn#35029 mdn#35030

Sacrafex requested a review from a team as a code owner February 28, 2026 03:53

Sacrafex requested review from hamishwillee and removed request for a team February 28, 2026 03:53

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Merge branch 'main' into patch-1

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Update files/en-us/web/css/reference/values/url_value/index.md

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Update files/en-us/web/css/reference/values/url_value/index.md

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Update files/en-us/web/css/reference/values/url_value/index.md

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Co-authored-by: Estelle Weyl <estelle@openwebdocs.org>

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Sacrafex and others added 3 commits March 2, 2026 10:33

Specify that URL must be absolute or relative

e44959d

Clarified the URL value requirement in the documentation.

Update files/en-us/web/css/reference/values/url_value/index.md

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Update CORS information for <url> value in CSS

decf234

Clarified CORS validation requirements for CSS properties using <url> values and added information about local file access issues.

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Sacrafex requested a review from estelle March 2, 2026 18:58

Merge branch 'main' into patch-1

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Co-authored-by: Estelle Weyl <estelle@openwebdocs.org>

Update URL value syntax and descriptions

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Clarified the description of URL values and updated examples.

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github-actions bot added size/m [PR only] 51-500 LoC changed and removed size/s [PR only] 6-50 LoC changed labels Mar 3, 2026

Merge branch 'main' into patch-1

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Co-authored-by: Hamish Willee <hamishwillee@gmail.com>

Merge branch 'main' into patch-1

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Update CORS validation details for CSS url values

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Clarified CORS requirements for certain CSS properties referencing external resources.

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hamishwillee merged commit 95f5082 into mdn:main Mar 8, 2026
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Sacrafex commented Feb 28, 2026

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