Highlight currently active page in sidebar docs navigation

[harshitkandpal]

Description

This PR addresses a minor documentation UI issue where the currently viewed page is not visually highlighted or distinguished in the sidebar navigation. This can make it disorienting to know exactly which section a reader is currently browsing.

I have updated the custom extra.css file to target the theme's active navigation link component (a.md-nav__link.md-nav__link--active), applying a bold font-weight and utilizing the project's pre-defined --md-accent-fg-color branding token. This ensures a clear visual cue that remains seamless across both light and dark modes without highlighting the entire parent category header accidentally.

Related Discussion

As requested in the contributing guidelines, this pull request follows an approved proposal:
Fix #9992

Checklist

• I have read the CONTRIBUTING.md document.
• My changes only affect the documentation styling (extra.css) and do not modify core logic.
• Verified locally using mkdocs serve across pages.

[harshitkandpal]

Hey @browniebroke
just a quick heads-up that I've submitted the PR for this here: #9993. All the automated checks passed, so it’s ready for your review whenever you have a moment. Thanks!

Accessibility issue found

[harshitkandpal]

Hey @browniebroke,
thanks for the review! That makes total sense regarding the contrast ratio.

I've updated the CSS selector to use the --md-accent-fg-color--dark token as you suggested so it fully complies with the WCAG AA accessibility standards. All the CI checks have passed successfully again. Ready for another look whenever you have a moment!

[browniebroke]

Thanks!

[harshitkandpal]

Thanks @browniebroke!
It's a pleasure to be able to help out and contribute back to the open-source community.
Glad I could help make the docs a little easier to navigate! ☺️