main.js

const popup = document.querySelector(".popup");
const close = document.querySelector(".close");
window.onload = function () {
  setTimeout(function () {
    popup.style.display = "block";
  }, 500);
};

close.addEventListener("click", () => {
  popup.style.display = "none";
});

var coll = document.getElementsByClassName("collapsible");
var i;

for (i = 0; i < coll.length; i++) {
  coll[i].addEventListener("click", function () {
    this.classList.toggle("active");
    var collapsecontent = this.nextElementSibling;
    if (collapsecontent.style.maxHeight) {
      collapsecontent.style.maxHeight = null;
    } else {
      collapsecontent.style.maxHeight = collapsecontent.scrollHeight + "px";
    }
  });
}