An adaptation of snowfall CSS3 from http://www.techumber.com/2012/12/amazing-snow-fall-effect-using-pure-css3.html, for /r/Frozen.

snow.css

@keyframes snow {
    0% {background-position: 0px 0px, 0px 0px, 0px 0px;}
    50% {background-position: 500px 500px, 100px 200px, -100px 150px;}
    100% {background-position: 500px 1000px, 200px 400px, -100px 300px;}
}

@-moz-keyframes snow {
    0% {background-position: 0px 0px, 0px 0px, 0px 0px;}
    50% {background-position: 500px 500px, 100px 200px, -100px 150px;}
    100% {background-position: 400px 1000px, 200px 400px, 100px 300px;}
}

@-webkit-keyframes snow {
    0% {background-position: 0px 0px, 0px 0px, 0px 0px;}
    50% {background-position: 500px 500px, 100px 200px, -100px 150px;}
    100% {background-position: 500px 1000px, 200px 400px, -100px 300px;}
}

@-ms-keyframes snow {
    0% {background-position: 0px 0px, 0px 0px, 0px 0px;}
    50% {background-position: 500px 500px, 100px 200px, -100px 150px;}
    100% {background-position: 500px 1000px, 200px 400px, -100px 300px;}
}

.self.thing .entry {
    background-color: #96C8FD;
    background-image: url('http://demo.techumber.com/snowfallcss3/img/s1.png'), url('http://demo.techumber.com/snowfallcss3/img/s2.png'), url('http://demo.techumber.com/snowfallcss3/img/s3.png');
    -webkit-animation: snow 10s linear infinite;
    -moz-animation: snow 10s linear infinite;
    -ms-animation: snow 10s linear infinite;
    animation: snow 10s linear infinite;
}