Increase color contrast for links color with rendered docs in dark-mode

[d33bs]

The rendered docs in dark-mode show pink links which are a bit harder to read due to their lower color contrast (in comparison with the light-mode documentation). This issue pertains to increasing the color contrast to meet WCAG standards.

• Current color contrast for dark-mode links: https://webaim.org/resources/contrastchecker/?fcolor=8A2398&bcolor=000000
• Suggested color contrast for dark-mode links: https://webaim.org/resources/contrastchecker/?fcolor=D376E0&bcolor=000000

We may need to differentiate the styles for light-mode and dark-mode with this regard.