Kilotest: Diagnoses of code invalid violation by HTML element 626 on Mozilla Foundation page

Basics

About the page

• URL: https://www.mozilla.org/en-US/
• Tested 32 days ago on 2026-09-08 at 04:02 by job 260908T0359-xmh
• Summary of results:
  • Rule engines:
    • Called: 12
    • Were able to test: 12
    • Reported any rule violations: 11
  • Violations: 753
  • Violators: 192
  • Issues: 47
• Download the full technical report (JSON)

About the issue

• Why it matters: Invalid code in the page may prevent a helper from working
• Priority: high
• Related WCAG standard: 4.1
• Reported by 1 rule engine (Html Checker API)
• Violations: 1
• Violators: 1

About the violator

• Tag name: HEADER
• Text: Get Firefox news
• Start tag: <header class="mzp-c-newsletter-header">
• XPath: /html/body/div[2]/footer[1]/div[1]/div[1]/div[2]/form[1]/header[1]
• Bounding box: [not obtained]
• Reported by Html Checker API

Take me there

Diagnoses

Here is how rule engines diagnose the code invalid issue for HTML element 626 of the Mozilla Foundation page.

1. The element header must not appear as a descendant of the footer element.

   Rule engine: Html Checker API (World Wide Web Consortium)