.snow{
    position: fixed;
    left: 0px;
    top: 0px;
    width: 100%;
    height: 100%;
    z-index: 9999;
    pointer-events: none;
}
.snow > div{
    width: 100%;
    height: 100%;
    position: absolute;
}
.snow > .big{
    background-image: url("../images/falling-snow1.png");
    animation-name: snow-big;
    animation-duration: 25s;
    animation-timing-function: linear;
    animation-iteration-count: infinite;
    opacity: 0.25;
}
.snow > .small{
    background-image: url("../images/falling-snow2.png");
    animation: snow-small 52s linear infinite;
    opacity: 0.4;
}

@keyframes snow-big {
    0% {
        background-position-y: 0px;
    }

    100% {
        background-position-y: 2000px;
    }
}
@keyframes snow-small {
    0% {
        background-position-y: 0px;
    }
    100% {
        background-position-y: 2000px;
    }
}