Kilotest: Diagnoses of box size absolute violation by HTML element 464 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: User cannot enlarge the content of an item for readability
• Priority: high
• Related WCAG standard: 1.4.4
• Reported by 1 rule engine (QualWeb)
• Violations: 14
• Violators: 14

About the violator

• Tag name: SOURCE
• Text: [not applicable]
• Start tag: <source media="(max-width: 1311px)" srcset="https://www.mozilla.org/media/cms/images/download.2e16d0ba.fill-400x200.png 400w, https://www.mozilla.org/media/cms/images/download.2e16d0ba.fill-600x300.png 600w, https://www.mozilla.org/media/cms/images/download.2e16d0ba.fill-800x400.png 800w, https://www.mozilla.org/media/cms/images/download.2e16d0ba.fill-1000x500.png 1000w, https://www.mozilla.org/media/cms/images/download.2e16d0ba.fill-1200x600.png 1200w, https://www.mozilla.org/media/cms/images/download.2e16d0ba.fill-1400x700.png 1232w" sizes="(min-width: 768px) calc((100vw - 32px) / 2), calc(100vw - 32px)" width="1400" height="700">
• XPath: /html/body/div[2]/main[1]/section[1]/div[1]/div[1]/div[6]/div[1]/picture[1]/source[1]
• Bounding box: x = 1200, y = 3372, width = 0, height = 0
• Reported by QualWeb

Diagnoses

Here is how rule engines diagnose the box size absolute issue for HTML element 464 of the Mozilla Foundation page.

1. [failed] The test target `width` attribute uses absolute units.

   Rule engine: QualWeb (University of Lisbon)

   Rule: QW-BP15