// Keeps the CSS custom property --scroll-y on :root in sync with window.scrollY.
// CSS handles all scroll-linked animation math from there.

let rafPending = false;

function updateScrollVariables() {
    // Unitless: Firefox does not coerce <length>→<number> in calc(), so the
    // whole scroll pipeline stays in number space end-to-end.
    document.documentElement.style.setProperty("--scroll-y", window.scrollY);
    rafPending = false;
}

// Coalesce N scroll/resize events per frame into one rAF-timed DOM write.
// Dropping intermediate events is safe — rAF reads the latest scrollY on fire.
function handleScrollEvent() {
    if (rafPending) return;
    rafPending = true;
    requestAnimationFrame(updateScrollVariables);
}

// Initial sync write so --scroll-y reflects reality before first paint;
// hash-nav and restored scroll positions would otherwise flash unscrolled.
updateScrollVariables();

// scroll: passive so the browser doesn't wait on us before scrolling.
// resize events aren't cancellable, so the hint is unnecessary there.
window.addEventListener("scroll", handleScrollEvent, { passive: true });
window.addEventListener("resize", handleScrollEvent);

// Popover API shim
if (!("popover" in HTMLElement.prototype)) {
  // load fallback behavior, or use your old menu code
};

CustomElementRegistry.prototype.apply = function(tag, component) {
    if (!(!!component.constructor && component.toString().substring(0,5) == "class")) { return };
    if (this.get(tag)) { return };
    if (this.getName(component)) { return };
    try { this.define(tag, component) } catch(err) {
        console.debug(`component ${component.name} already registered as <${tag}>`);
    };
};