[core] Change $pt-link-color from $blue2 to $blue3

[ggdouglas]

Changes

Adjust the color of links in Blueprint from $blue2 (#215DB0) to $blue3 (#2D72D2)

Context

The style of links in Blueprint currently defaults to blue text that gets an underline on hover. This runs up against the recommendations in WCAG 1.4.1 around the use of color to distinguish links from a body of surrounding text. WCAG provides a compliant approach with Technique G183 that has the following three requirements:

Use of Color a relative luminance (lightness) difference of 3:1 or greater with the text around can be used. This technique goes beyond the success criterion and asks for visual highlights when the user hovers over each link, such as an underline, a change in font style such as bold or italics, or an increase in font size. Such a hover effect provides confirmation to pointer users that the text is a link, similar to how the link alters its appearance for keyboard users when it receives focus, in order to meet 2.4.7 Focus Visible.

We meet the later two criteria (underline on hover, outline on focus), but do not currently have a contrast of "3:1 or greater" with regards to our default body text and link text:

https://webaim.org/resources/linkcontrastchecker/?fcolor=1C2127&bcolor=FFFFFF&lcolor=215DB0

This change proposes increasing the luminance of links so that they meet his criteria:

https://webaim.org/resources/linkcontrastchecker/?fcolor=1C2127&bcolor=FFFFFF&lcolor=2D72D2

[changelog-app]

Generate changelog in packages/core/changelog/@unreleased

Type (Select exactly one)

• Feature (Adding new functionality)
• Improvement (Improving existing functionality)
• Fix (Fixing an issue with existing functionality)
• Break (Creating a new major version by breaking public APIs)
• Deprecation (Removing functionality in a non-breaking way)
• Migration (Automatically moving data/functionality to a new system)

Description

[core] Change $pt-link-color from $blue2 to $blue3

Check the box to generate changelog(s)

• Generate changelog entry

[svc-palantir-github]

Change `$pt-link-color` from `$blue2` to `$blue3`

Build artifact links for this commit: documentation | landing | table | demo

This is an automated comment from the deploy-preview CircleCI job.