fix(links): adopt visited link colors from Firefox

[caugner]

Summary

Fixes #9958.

Problem

Visited links are not readable in Safari with the dark theme.

Solution

Define visited link colors rathern than relying on browser defaults, adopting the visited link colors of Firefox.

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Screenshots

What	Before	After
Safari / Dark
Chrome / Dark
Firefox / Dark
Safari / Light
Chrome / Light
Firefox / Light

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How did you test this change?

[AnujaRajput727]

Looks good from the design side!

[GHkrishna]

Wouldn't the name '--text-link-visited' be more appropriate than the '--text-visited'?
The latter might add to the confusion and mentioning the link specifically in the name will be a better approach.

[LeoMcA]

looks good!

[caugner]

Wouldn't the name '--text-link-visited' be more appropriate than the '--text-visited'? The latter might add to the confusion and mentioning the link specifically in the name will be a better approach.

Excellent question! The CSS Color Module draft defines LinkText and VisitedText, which probably relate to the CSS selectors :link and :visited, so that's why I named the variable --text-visited. 🙂

[GHkrishna]

Wouldn't the name '--text-link-visited' be more appropriate than the '--text-visited'? The latter might add to the confusion and mentioning the link specifically in the name will be a better approach.

Excellent question! The CSS Color Module draft defines LinkText and VisitedText, which probably relate to the CSS selectors :link and :visited, so that's why I named the variable --text-visited. 🙂

Makes sense.