http://validator.w3.org/ checks markup (HTML, XHTML, SVG etc.), not CSS.
http://jigsaw.w3.org/css-validator/ checks CSS, not markup.
Answer from unor on Stack OverflowW3C
jigsaw.w3.org
Jigsaw Overview
The Jigsaw software provides the Consortium's Java-based Web server. With a modular architecture and full HTTP/1.1 compliance, the Jigsaw server is a premier experimental platform for W3C and the Internet community.
W3C
jigsaw.w3.org › css-validator
The W3C CSS Validation Service - Jigsaw
Check Cascading Style Sheets (CSS) and (X)HTML documents with style sheets · Enter the URI of a document (HTML with CSS or CSS only) you would like validated:
W3C
w3.org › Jigsaw
Jigsaw - W3C's Server
Jigsaw is W3C's leading-edge Web server platform, providing a sample HTTP 1.1 implementation and a variety of other features on top of an advanced architecture implemented in Java. The W3C Jigsaw Activity statement explains the motivation and future plans in more detail.
W3C
jigsaw.w3.org › new.html
Jigsaw Overview - W3C
The current work on Jigsaw is focused on stability and HTTP/1.1 comformance, thanks to the great work done on CoAdvisor by The Measurement Factory.
W3C
jigsaw.w3.org › index.html
World Wide Web Consortium
The World Wide Web Consortium (W3C) develops interoperable technologies (specifications, guidelines, software, and tools) to lead the Web to its full potential. W3C is a forum for information, commerce, communication, and collective understanding. On this page, you'll find W3C news, links to W3C technologies and ways to get involved.
W3C
w3.org › Jigsaw › Overview.html
Jigsaw Overview - W3C's Server
Jigsaw is W3C's leading-edge Web server platform, providing a sample HTTP 1.1 implementation and a variety of other features on top of an advanced architecture implemented in Java. The W3C Jigsaw Activity statement explains the motivation and future plans in more detail.
YouTube
youtube.com › tech talk tutorials
How To Validate Your CSS3 Code Using An Online Validation Service | Jigsaw.W3C.org | *2023* - YouTube
How To Validate Your CSS Code Using An Online Validation Service | Jigsaw.W3C.org | *2023*This will be a video tutorial on how to find and fix CSS3 coding er...
Published January 8, 2023
W3C
jigsaw.w3.org › css-validator › manual.html
CSS Validator User Manual - Jigsaw - W3C
If you want to use W3C's public validation server, use the parameters below in conjunction with the following base URI: https://jigsaw.w3.org/css-validator/validator replace with the address of your own server if you want to call a private instance of the validator.
W3C
jigsaw.w3.org › css-validator › api.html
Documentation of the Programmatic Interface (API) to The W3C CSS Validation Service
<?xml version='1.0' encoding="utf-8"?> ...w3.org/2003/05/soap-encoding" xmlns:m="http://www.w3.org/2005/07/css-validator"> <m:uri>http://www.w3.org/</m:uri> <m:checkedby>http://jigsaw.w3.org/css-validator/</m:checkedby> <m:csslevel>css2</m:csslevel> <m:date>2006.02.23T01:19:57Z</m:date> ...
Joomlapolis
joomlapolis.com › forum › support and presales › professional members support › css errors .http://jigsaw.w3.org/css-validator/
CSS errors . - Joomlapolis Forum
December 21, 2013 - semco wrote: Don't say never "no website will ever be clean of W3 validation error" Just check this jigsaw.w3.org/css-validator/validator?uri=http://www.market-ing.ca&profile=css3&usermedium=all&warning=1&vextwarning=&lang=en Thank You for Your repay Any website with modern CSS likely won't validate.
W3C
jigsaw.w3.org › css-validator › DOWNLOAD.html
Download and Install the CSS Validator - Jigsaw - W3C
While the official service from W3C runs under the Jigsaw server (which is the recommended setup), we will for the sake of convenience describe in this guide the setup under Apache's servlet engine, Tomcat, as well as some quick instructions for Jigsaw and commandline usage.
GitHub
github.com › w3c › css-validator › issues › 235
Which tool can I trust, css-validator.org or jigsaw.w3.org/css-validator? · Issue #235 · w3c/css-validator
May 2, 2019 - I am looking at some CSS custom properties right now, which are error free in css-validator.org. The same CSS trows parse errors in jigsaw.w3.org/css-validator.
Author jonasjacek
W3C
jigsaw.w3.org › css-validator › about.html
About the W3C CSS Validation Service - Jigsaw
Check Cascading Style Sheets (CSS) and (X)HTML documents with style sheets · The W3C CSS Validation Service is a free software created by the W3C to help Web designers and Web developers check Cascading Style Sheets (CSS). It can be used on this free service on the web, or downloaded and used ...
Team Treehouse
teamtreehouse.com › community › validatorw3org-and-jigsaww3org
validator.w3.org and jigsaw.w3.org (Example) | Treehouse Community
June 19, 2014 - Charles Harpke is having issues with: When an error is found, is there a repository on the site itself, or knowledge base to correct your own code. My index.html generated 3 error...
SitePoint
sitepoint.com › html & css
Css validator - HTML & CSS - SitePoint Forums | Web Development & Design Community
August 23, 2023 - I believe that the official validator is https://jigsaw.w3.org/css-validator/ and is the correct one as its hosted by the w3c and linked to in their documentation whereas https://css-validator.org/ is not the official validator even though it may have a similar codebase.
W3C
w3.org › Jigsaw › Activity.html
Jigsaw Activity Statement
The Jigsaw software provides the Consortium's Java-based Web server. With a modular architecture and full HTTP/1.1 compliance, the Jigsaw server is a premier experimental platform for W3C and the Internet community.
W3C
w3.org › Jigsaw › Doc › FAQ.html
Jigsaw Frequently asked questions
Jigsaw implements its own persistence mechanism while RMI already provides a way to serialize objects, why is it so, will it change ? What Jigsaw implements in the w3c.tools.store package is more then persistence. It provides both a way of serializing objects and a way of describing what and how the object will be dumped.