[Eugene (OEvgeny)]

Fixes #5713

Changelog Entry

Fixed

• Fixed the "Positive" card action button having less than 4.5:1 color contrast, fixes #5713, in PR #5905, by @OEvgeny

Description

The "Positive" card action button had white text on #0078d7, just under the 4.5:1 contrast required by WCAG 1.4.3, in the default and Fluent themes. It now uses #0078d4 (4.53:1), which looks the same.

Design

• #0078d4 is the nearest blue that passes; Fluent's #0f6cbd would pass by more, but would look almost the same as a selected action (#0063b1, Announce card action buttons as buttons, describe pressed actions as Selected #5900).
• The new test also renders the card outside of the transcript: inside it, the transcript focus overlays cover the card, so the accessibility check reports its contrast as "incomplete" instead of failing.
• Announce card action buttons as buttons, describe pressed actions as Selected #5900 edits other rules in the same CSS file: the two merge cleanly in either order, except for neighboring CHANGELOG lines.

Specific Changes

• AdaptiveCardRenderer.module.css: the background of the Positive button is #0078d4 instead of #0078d7

• Added richCard/actionStyles.contrast.html and its Fluent variant: the "card actionstyles" card, in the transcript and outside of it, with the default accessibility check; fails on main with insufficient color contrast of 4.49

• I have added tests and executed them locally

• I have updated CHANGELOG.md

• I have updated documentation

Review Checklist

This section is for contributors to review your work.

• Accessibility reviewed (tab order, content readability, alt text, color contrast)
• Browser and platform compatibilities reviewed
• CSS styles reviewed (minimal rules, no z-index)
• Documents reviewed (docs, samples, live demo)
• Internationalization reviewed (strings, unit formatting)
• package.json and package-lock.json reviewed
• Security reviewed (no data URIs, check for nonce leak)
• Tests reviewed (coverage, legitimacy)

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