feat: fix a11y issues in expansion panel component

[fateeand]

Fixing accessibility issues in expansion panel component

Validation rules:

Validated using Playwright accessibility tests, Lighthouse tool, and manual checks including keyboard tab navigation and screen reader testing.

Full doc with rules

---

Playwright axe-core validation results:

State before:

Component	aria-roles	color-contrast	tabindex	target-size
Expansion panel	-	❌	-	-

---

State after:

Component	aria-roles	color-contrast	tabindex	target-size
Expansion panel	✅	✅	✅	✅

---

Checklist

• Keyboard Navigation
  All interactive elements are fully operable via keyboard only, including buttons, inputs, menus, dialogs, sliders, drag-and-drop, tree views, multi-selects, and composite widgets. No traps or dead ends.

• Focus Management
  Focus is visible, logical, moves in predictable order, trapped where necessary (modals/popovers), and restored after closing. Focus is perceivable in all interactive widgets.

• Semantics / ARIA

  • Semantic HTML is used correctly.
  • ARIA roles, states, and properties are applied only when needed.
  • All form fields, tables, and widgets (including autocomplete, tree selects, tree tables, drag-and-drop, sliders, and multi-selects) are properly labeled and accessible.

• Color / Contrast

  • Text and interactive elements meet contrast requirements (≥4.5:1 normal text, ≥3:1 large text).
  • Focus and selection indicators are visually perceivable.
  • Color is not the only indicator of state.

• Screen Reader / Assistive Technology

  • All content, labels, and dynamic updates are perceivable via screen readers.
  • Live regions announce status messages, alerts, modals, notifications, and dynamic changes.
  • Interactive widgets provide proper announcements of selection and updates.

• Responsive & Zoom

  • Components function correctly and remain readable at all viewport sizes and up to 200% zoom, including mobile and touch devices.
  • Prefer em/rem units over px where scaling is required.

• [N/A] Error Handling

  • Errors are clearly identified visually and programmatically.
  • Form inputs use aria-describedby or aria-invalid for inline messages.
  • Instructions and suggestions are accessible.

• [N/A] Dynamic Content / Updates

  • Status updates, alerts, notifications, and modals use live regions.
  • Updates do not disrupt focus or user control unexpectedly.

• Interaction Feedback / States

  • All interactive states (hover, focus, active, disabled, drag-and-drop, reordering, multi-select) are visually perceivable.

• [N/A] Authentication & Sensitive Actions

  • Inputs and actions involving sensitive data provide accessible instructions, feedback, and error messages.

• Predictable & Controllable UI

  • Components behave consistently and predictably.
  • Popups, modals, autocomplete suggestions, drag-and-drop, and dynamic content allow user control.

---

Release notes:

• Fix a11y issues in expansion panel component

[github-actions]

Coverage report for library

St.❔	Category	Percentage	Covered / Total
🔴	Statements	48.49%	3542/7305
🔴	Branches	44.61%	1590/3564
🔴	Functions	46.96%	664/1414
🔴	Lines	49.06%	3300/6726

Test suite run success

1208 tests passing in 34 suites.

Report generated by 🧪jest coverage report action from 937bf7e

[github-actions]

Playwright test results

 88 passed

Details

 88 tests across 4 suites
 3 minutes, 2 seconds
 937bf7e
 For details, download the Playwright report

[Copilot]

Pull request overview

This PR improves the accessibility of CpsExpansionPanelComponent by adding proper ARIA semantics, keyboard interaction handling, and focus styling, and then re-enables automated Playwright axe validation for the expansion panel example page.

Changes:

• Add ARIA roles/attributes (role="button", aria-expanded, aria-controls, aria-hidden) and keyboard handlers to the expansion panel header/content.
• Update styling to include an accessible focus ring and switch several hard-coded px values to rem.
• Expand unit test coverage for new accessibility behavior and re-enable the expansion panel in Playwright accessibility scans.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
projects/cps-ui-kit/src/lib/components/cps-expansion-panel/cps-expansion-panel.component.ts	Adds unique content IDs, keyboard interaction state, and runtime conversions for style inputs.
projects/cps-ui-kit/src/lib/components/cps-expansion-panel/cps-expansion-panel.component.html	Adds ARIA semantics and keyboard event wiring; switches to converted style inputs.
projects/cps-ui-kit/src/lib/components/cps-expansion-panel/cps-expansion-panel.component.scss	Adds focus-visible styling via shared focus-ring mixin; converts sizing from px to rem.
projects/cps-ui-kit/src/lib/components/cps-expansion-panel/cps-expansion-panel.component.spec.ts	Updates defaults and adds tests for ARIA attributes, keyboard interaction, and unique IDs.
projects/composition/src/app/pages/expansion-panel-page/expansion-panel-page.component.ts	Imports CpsButtonComponent for the updated example content.
projects/composition/src/app/pages/expansion-panel-page/expansion-panel-page.component.html	Updates examples (adds a button; switches some values to rem-based inputs).
projects/composition/src/app/pages/expansion-panel-page/expansion-panel-page.component.scss	Converts example layout spacing from px to rem.
projects/composition/src/app/api-data/cps-expansion-panel.json	Updates API docs description for borderRadius.
playwright/cps-accessibility.spec.ts	Re-enables expansion panel route in axe scanning list with a page-scoped selector.