Element that sticks to the top of the page on scroll
var element = document.querySelector(".element"),
stop = element.offsetTop - 0,
docBody = document.documentElement ||
document.body.parentNode ||
document.body,
hasOffset = window.pageYOffset !== undefined,
scrollTop;
window.onscroll = function() {
scrollTop = hasOffset ? window.pageYOffset : docBody.scrollTop;
if (scrollTop >= stop) {
element.className = 'element stick';
} else {
element.className = 'element';
}
}