The 404 and 403 pages have no h1

Problem/Motivation

On a Horizon Aid site the "Page not found" page renders only its message, with no h1. Canvas renders the page regions, so the theme's page title block never shows on system pages. This fails WCAG 2.2 AA (page-has-heading-one).

Steps to reproduce

1. Install Drupal CMS with the Horizon Aid site template.
2. Visit /this-page-does-not-exist logged out: no h1.

Proposed resolution

• Render the page title as the h1 on the 404 and 403 pages, the way the user login page already does.

Remaining tasks

• ✅ File an issue
• ✅ Addition/Change/Update/Fix
• ✅ Testing to ensure no regression
• ➖ Automated unit/functional testing coverage
• ➖ Developer Documentation support
• ➖ User Guide Documentation support
• ➖ UX/UI designer responsibilities
• ✅ Accessibility and Readability
• ❌ Reviewed by a human
• ❌ Code review by maintainers
• ❌ Full testing and approval
• ❌ Credit contributors
• ❌ Review with the product owner
• ✅ Update Release Notes
• ✅ Release

User interface changes

• The 404 and 403 pages show their title as a heading.

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• The 404 and 403 pages render their title as the h1.

AI-Generated: Yes