.snow {
    /*雪の色*/
    color: snow;
    /*雪の大きさ*/
    font-size: 10px;
    /*初期位置*/
    position: fixed;
    top: -5%;
    /*雪を適当な幅で降らせる*/
    text-shadow:
    5vw   -100px 2px,
    10vw  -400px 3px,
    20vw  -500px 4px,
    30vw  -580px 1px,
    39vw  -250px 2px,
    42vw  -340px 5px,
    56vw  -150px 2px,
    63vw  -180px 0,
    78vw  -220px 4px,
    86vw  -320px 9px,
    94vw  -170px 7px;
    /*雪アニメーション1*/
    animation: roll 5s linear infinite;
    z-index: 101;
}
/*2つめの雪アニメーション*/
.snow2nd{animation: anim 8s linear infinite;}

@keyframes roll {
    0% {transform:rotate(0deg);}
    90% {opacity:1;}
    100% {transform:rotate(20deg);top:100%;opacity:0;}
}
@keyframes anim {
    100% {color:transparent;top:150%;}
}