https://cleanemail.com/user/sites/cleanemail.com/pages/parts/sign-up-slide-out/sync.js

1document.addEventListener("DOMContentLoaded", function() {
2    let element = document.getElementById("sign-up-slide-out")
3    const observer = new IntersectionObserver(($event) => {
4        let isAnyIntersecting = !!$event.reduce((previousValue, currentValue) => { return previousValue + (currentValue.isIntersecting ? 1 : 0) }, 0);
5        if (isAnyIntersecting) {
6            element.classList.remove("active")
7        } else {
8            element.classList.add("active");
9        }
10    });
11    document.querySelectorAll(".observable-sign-up-form").forEach(container => {
12        observer.observe(container)
13    })
14});