script.js

const sectionLinks = [...document.querySelectorAll('.site-nav a[href^="#"]')];
const sections = sectionLinks
  .map((link) => document.querySelector(link.getAttribute("href")))
  .filter(Boolean);

if ("IntersectionObserver" in window && sections.length) {
  const observer = new IntersectionObserver(
    (entries) => {
      const active = entries
        .filter((entry) => entry.isIntersecting)
        .sort((a, b) => b.intersectionRatio - a.intersectionRatio)[0];

      if (!active) return;
      sectionLinks.forEach((link) => {
        const matches = link.getAttribute("href") === `#${active.target.id}`;
        if (matches) link.setAttribute("aria-current", "location");
        else link.removeAttribute("aria-current");
      });
    },
    { rootMargin: "-28% 0px -58%", threshold: [0.12, 0.4, 0.7] },
  );

  sections.forEach((section) => observer.observe(section));
}