GitHub links fail accessibility guidelines because they rely on colour

[andrewhick]

Issue

The default link format on GitHub appears to fail Web Content Accessibility Guideline (WCAG) criterion 1.4.1 Use of Colour (level A). This is because without hovering, the only way of identifying these links is by being able to distinguish blue and dark grey text. This is therefore likely to make it harder for people with low colour vision to identify links.

To Reproduce

1. Go to a standard GitHub README or wiki page, such as https://github.com/github
2. Check the formatting of any links
3. Using Chrome dev tools, the link colour appears to be: --colour-accent-fg: #0969da
4. The surrounding text colour appears to be: --color-fg-default: #24292f
5. Using colour contrast analyser, the contrast ratio between these 2 colours is around 2.8:1.

Expected behaviour

To meet WCAG level A, links should have a way other than colour (hue) to help identify them, such as underlining them. Alternatively, the contrast ratio between the colours of the links and surrounding text should be at least 3:1 to meet the standard required by WCAG.

Desktop

• OS: Windows 10 Pro
• Browser: Chrome
• Version: 102.0.5005.63
• Default display settings

Additional context

We are using the GitHub wiki to publish Government Digital Service guidance on accessibility but would like the platform itself to meet the standards we refer to.

[github-actions]

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