https://polarbreeze.at/js/product_page_v4_favicon.js

1window.addEventListener('load', () => {
2	const faviconMeta = document.getElementById('favicon-theme-color');
3	const faviconObserver = document.getElementById('favicon-observer');
4
5	const observer = new IntersectionObserver((entries) => {
6		entries.forEach((entry) => {
7			if (entry.isIntersecting) {
8				const visibleColor = favicon_vars.faviconObserver;
9				if (faviconMeta) {
10					faviconMeta.setAttribute('content', visibleColor);
11				}
12			} else {
13				const hiddenColor = favicon_vars.faviconColor;
14				if (faviconMeta) {
15					faviconMeta.setAttribute('content', hiddenColor);
16				}
17			}
18		});
19	});
20
21	if (faviconObserver) {
22		observer.observe(faviconObserver);
23	}
24});