[a11y][Violation][1.3.1 Info and Relationships] Table Headers Do not meet WCAG 2.2 Requirements

[nkn2022]

Description

I am running an accessibility test suite with Notebook UI using the IBM Equal Access Accessibility Checker tool on Chrome browser. The results look good overall, only a few things are missing to reach a first formal level of compliance. So kindly help look into these.

Issues reported were violating WCAG 2.2 requirements.
Ref: https://www.ibm.com/able/requirements/checker-rule-sets

Full report (includes information on element locations where issue were found):
Accessibility_Report-7a73e10e-f8a4-4a06-a78d-5174a1309c5b.xlsx

Category: 1.3.1 Info and Relationships

Ref: https://www.ibm.com/able/requirements/requirements/?version=v7_3#1_3_1

Violation of Rule: table_headers_related

List of issues with elements that violate this rule with a screenshots

Issue 1
Complex table does not have headers for each cell properly defined with 'header' or 'scope'
Element location:
<th>
Screenshot:

Reproduce

• Install Chrome extension for IBM accessibility checker tool. Ref: https://www.ibm.com/able/toolkit/verify/automated
• Open Notebook UI on Chrome browser. Add some cells with code.
• Run the tool and we can see the above Violations reported.

Here is the screenshot of the UI scanned for the attached report:

Expected behavior

Table headers are correctly defined.
Reference on how to fix this issue can be found in these links:
https://www.ibm.com/able/toolkit/develop/text-and-non-text/#headings

[RRosio]

Per triage meeting: This could potentially require upstream changes in JupyterLab's markdownviewer.