Add navbar scroll-spy active state for section links

[Cbiux]

Summary

Navbar section links do not indicate which part of the page the user is viewing. A scroll-spy active state improves orientation on long landing pages.

What to build

• In components/landing/landing-nav.tsx, track the visible section via IntersectionObserver or scroll position
• Highlight the active nav link (e.g. text-white + underline, matching hover style)
• Update active state on scroll and when clicking anchor links
• Works on desktop nav; optional on mobile menu

Acceptance criteria

• Active section link is visually distinct while scrolling
• No layout shift or jank on fast scroll
• Respects prefers-reduced-motion if issue Respect prefers-reduced-motion on landing animations #12 is merged first
• npm run build passes

Files

• components/landing/landing-nav.tsx
• lib/landing-nav.ts (if shared nav config from Sync navbar and footer links with all landing sections #11 exists)

---

How to contribute

1. Comment before starting
2. Fork → branch (feat/nav-scroll-spy)
3. Test at 375px and 1280px viewports
4. PR with Closes #14

Part of the GrantFox OSS program.

[YfengJ]

Hi, I would like to take this issue if it is available.\n\nPlanned approach:\n- add active-section tracking in the landing nav using IntersectionObserver with a safe scroll fallback if needed\n- visually distinguish the active desktop nav link without causing layout shift\n- keep anchor-click behavior and mobile menu behavior stable\n- verify at mobile and desktop widths, and run the production build\n\nI will wait for assignment or maintainer confirmation before opening a PR, so this follows the GrantFox workflow.

[leocagli]

I'd like to work on this issue, please assign me so I can begin implementation.