Issues

• CSS nesting check reports a spurious error

  w3c/css-validator#521 · Filter by author vadimkantorov opened on Sep 29, 2026

• Misleading parse error

  w3c/css-validator#520 · Filter by author dirk-zimoch opened on Sep 11, 2026
  1

• Not recognizing calc result as number, nor recognizing @property

  w3c/css-validator#518 · Filter by author nickchomey opened on Aug 29, 2026

• Usage of field-sizing: content; returns error

  w3c/css-validator#514 · Filter by author HowDoes opened on Jul 4, 2026

• CSS checker enhancement request; output full details of each error’s location, including errors inside @imports

  enhancement
  w3c/css-validator#491 · Filter by author CecilSWard opened on Mar 12, 2026

• CSS checker request for enhancement; scanning the contents of @imports should be an option

  enhancement
  w3c/css-validator#490 · Filter by author CecilSWard opened on Mar 12, 2026

• issue with test testsuite/bugs/4469.css

  w3c/css-validator#487 · Filter by author tenzap opened on Mar 8, 2026
  2

• CSS clip-path w/o path()

  w3c/css-validator#480 · Filter by author xerc opened on Feb 18, 2026

• False error for SVG-related properties x, y, d, r, rx, ry, cx, cy

  w3c/css-validator#477 · Filter by author 1jj opened on Jan 20, 2026

• Property does not exist error on container queries

  w3c/css-validator#474 · Filter by author abbott567 opened on Dec 19, 2025

• CSS path() gives error when used for clip-path

  enhancement
  w3c/css-validator#472 · Filter by author samhed opened on Dec 11, 2025
  1

• Property clip-path:polygon() with reference box causes warning

  w3c/css-validator#471 · Filter by author atarax42 opened on Dec 11, 2025

• Custom protocol reported as invalid

  w3c/css-validator#466 · Filter by author hubertgajewski opened on Nov 18, 2025
  1

• validation by file upload fails on tomcat 11 (Unable to process parts as no multi-part configuration has been provided)

  w3c/css-validator#455 · Filter by author tenzap opened on Jul 6, 2025
  5

• Exception in IndexGenerator::generatesIndex when served as deployed war

  w3c/css-validator#451 · Filter by author tenzap opened on Jun 27, 2025

• LICENSE.md vs COPYRIGHT.html

  w3c/css-validator#447 · Filter by author tenzap opened on Jun 8, 2025

• Parse error

  w3c/css-validator#445 · Filter by author boris-petrov opened on May 23, 2025
  3

• Support: template element attributes

  w3c/css-validator#433 · Filter by author lukejans opened on Dec 27, 2024

• Validator returns "Congratulations! No Error Found." for CSS with syntax errors in it

  w3c/css-validator#429 · Filter by author kupietools opened on Sep 28, 2024

• Only validator - no dependencies

  w3c/css-validator#428 · Filter by author Limraj opened on Sep 18, 2024

• Unrecognized at-rule @container

  w3c/css-validator#422 · Filter by author PitWenkin opened on Jun 10, 2024

• Cast exception when validating @font-face rule with CSS level 2 profile

  w3c/css-validator#416 · Filter by author correctmost opened on Mar 20, 2024

• Possible false validation error "Property d doesn't exist."

  enhancementSVG
  w3c/css-validator#403 · Filter by author oldrup opened on Jun 19, 2023
  1

  

• Incorrect css shows as correct

  w3c/css-validator#398 · Filter by author em92 opened on Apr 8, 2023
  1

• image-set property is reported as an error... incorrectly

  w3c/css-validator#388 · Filter by author KevinGIRAULT opened on Nov 17, 2022
  2