Pls never forget

floatingbar.js

window.addEventListener("scroll", function() {
  var spoiler = document.getElementById("spoiler2");
  var div = document.getElementsByClassName("problem")[0];

  var divs = document.querySelectorAll(".divspoiler");
  var spoilers = document.querySelectorAll("input[id^=\"spoiler\"]");
  //console.log(labels);

  var divsfratop = [];
  divs.forEach(function(item, index) {
    divsfratop.push(item.getBoundingClientRect().y | 0);
  });

  var found_spoiler = false;
  for(var i = divsfratop.length-1; i >= 0; i--) {
    if(!found_spoiler && divsfratop[i] < 0) {
      spoilers[i].classList.add("stick");
      spoilers[i].setAttribute("style", "z-index: 1;");
      found_spoiler = true;
    } else {
      spoilers[i].classList.remove("stick");
      spoilers[i].setAttribute("style", "z-index: 0;");
    }
  }
});