var limit = document.getElementsByClassName('blog');
var overlay = document.createElement('div');
var body = document.getElementsByTagName('body');


overlay.classList.add("popup-overlay");
overlay.style = "width: 100%; height: 100%; opacity: 0.9; background-color: black; z-index: 999998; position: fixed; visibility: hidden; overflow: hidden;";
limit[0].insertBefore(overlay, body[0].childNodes[0]); // Estabelecer limite de mouse over

body[0].childNodes[2].addEventListener("mouseover", showPopup);

function showPopup () {
  overlay.style.visibility = "visible";
}