/* ScrollRail — vertical section indicator on the right. window.ScrollRail */ (function () { const { useState, useEffect, useRef } = React; window.ScrollRail = function ScrollRail({ items }) { const [active, setActive] = useState(0); const [hover, setHover] = useState(null); const elsRef = useRef([]); useEffect(() => { elsRef.current = items.map((it) => document.getElementById(it.id)); let raf = 0; const onScroll = () => { cancelAnimationFrame(raf); raf = requestAnimationFrame(() => { const mid = window.scrollY + window.innerHeight * 0.32; let idx = 0; elsRef.current.forEach((el, i) => { if (el && el.offsetTop <= mid) idx = i; }); setActive(idx); }); }; onScroll(); window.addEventListener("scroll", onScroll, { passive: true }); window.addEventListener("resize", onScroll); return () => { window.removeEventListener("scroll", onScroll); window.removeEventListener("resize", onScroll); }; }, [items.length, items.map(i => i.id).join("|")]); return ( ); }; })();