Kilotest: Diagnoses of invalid CSS at-rule violation by HTML element 0 on Wikimedia Foundation contact page

Basics

About the page

• URL: https://wikimediafoundation.org/contact/
• Tested 2 days ago on 2026-10-07 at 23:09 by job 261007T2305-3mn
• Summary of results:
  • Rule engines:
    • Called: 12
    • Were able to test: 12
    • Reported any rule violations: 11
  • Violations: 335
  • Violators: 166
  • Issues: 42
• Download the full technical report (JSON)

About the issue

• Why it matters: Page cannot be properly displayed in particular contexts
• Priority: high
• Related WCAG standard: 4.1
• Reported by 1 rule engine (Html Checker)
• Violations: 1
• Violators: 1

About the violator

• Tag name: HTML
• Text: [not applicable]
• Start tag: <html lang="en-US" style="--vh: 10.8px; --scrollbar: 0px;">
• XPath: /html
• Bounding box: x = 0, y = 0, width = 1920, height = 4544
• Reported by Html Checker

Diagnoses

Here is how rule engines diagnose the invalid CSS at-rule issue for HTML element 0 of the Wikimedia Foundation contact page.

1. CSS: Unrecognized at-rule @container Extract: w:span 1;}@container (max-

   Rule engine: Html Checker (World Wide Web Consortium)

   Rule: CSS: Unrecognized at-rule @container