https://www.voges-gemuese.de/files/01_basics/theme/scripts/anchor-points.js?v=ad16417a

1function ready(callback) {
2    if (document.readyState === "interactive" || document.readyState === "complete") {
3        callback()
4    } else {
5        function done() {
6            document.removeEventListener("DOMContentLoaded", done);
7            callback();
8        }
9
10        document.addEventListener("DOMContentLoaded", done);
11    }
12}
13
14const navHeight = document.querySelector(".navigation").offsetHeight;
15
16ready(() => {
17    if (window.location.hash) {
18        const element = document.querySelector(window.location.hash);
19        const top = element.getBoundingClientRect().top + window.pageYOffset - navHeight;
20    
21        window.scrollTo({ top, behavior: "smooth" });
22    }
23
24    document.querySelectorAll('a[href^="#"]').forEach(anchor => {
25        anchor.addEventListener("click", event => {
26            event.preventDefault();
27    
28            const element = document.querySelector(event.target.getAttribute("href"));
29            const top = element.getBoundingClientRect().top + window.pageYOffset - navHeight;
30    
31            window.scrollTo({ top, behavior: "smooth" });
32        });
33    });
34});