transparent image overlay (snowy)

body::after {
content: "";
position: fixed;
top: 0;
left: 0;
width: 100%;
height: 100%;
background-image: url(image url goes here);
opacity: .6;
background-size: 50%;
image-rendering: auto;
pointer-events: none;
}

replace "image url goes here" with an image address
this is the one i used:
https://img.pngio.com/snow-gifs-get-the-best-gif-on-giphy-snowing-transparent-480_480.gif