transform-origin: 0 100%;
a:after {
content: '';
width: 50px;
height: 50px;
position: absolute;
background-image: url(https://i.imgur.com/rWGmd4C.png)
}
$(window).scroll(function(evt) {
console.log(evt)
});
#id-facebook a {
position: relative;
z-index: 1;
}
#id-facebook a:after {
content: '';
position: absolute;
top: 0; right: 0; bottom: 0; left: 0;
background-image: url(...);
background-size: cover;
z-index: 2;
}
window.getComputedStyle(element).transform
height: 4vw;
width: 4vw;
https://jsfiddle.net/syb7kb65/