Intro
The scroll-spy TOC listens to which section is in view and highlights the matching link. Uses IntersectionObserver.
Work
When this block enters the viewport, the "02 / Work" link turns red. No libraries needed, about 15 lines of JavaScript.
About
Used by long-form editorial sites, documentation pages, and any portfolio with named sections.
Contact
The final section — once you reach here, the TOC is done and the user has a clear sense of where they've been.