Change link colors for aid in readability in dark mode.

[mmaloney-sf]

Contributor Checklist

• Did you add Scaladoc to every public function/method?
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• Did you delete any extraneous printlns/debugging code?
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Type of Improvement

• Feature (or new API)
• API modification
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• Performance improvement
• Bugfix
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• Dependency update
• Internal or build-related (includes code refactoring/cleanup)

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• Rebase: You will rebase the PR onto master and it will be merged with a merge commit.

Release Notes

Reviewer Checklist (only modified by reviewer)

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[jackkoenig]

This improves links in dark mode quite a bit, but the colors so far for light mode make the links too hard to see. I'm suggesting just switching back to blue for light mode then we can merge this as is and it's a huge improvement for dark mode at least.

I'm open to other colors for light mode links but at least at the moment, it's too hard to distinguish from regular dtext.