/* 星空背景动画 */
.hide {
    display: none;
}

@keyframes move-twink-back {
    from {background-position:0 0;}
    to {background-position:-10000px 5000px;}
}
@-webkit-keyframes move-twink-back {
    from {background-position:0 0;}
    to {background-position:-10000px 5000px;}
}

@keyframes move-clouds-back {
    from {background-position:0 0;}
    to {background-position:10000px 0;}
}
@-webkit-keyframes move-clouds-back {
    from {background-position:0 0;}
    to {background-position:10000px 0;}
}

.stars, .twinkling, .clouds {
    position:absolute;
    top:0;
    left:0;
    right:0;
    bottom:0;
    width:100%;
    height:100%;
    display:block;
}

/* Stars */
.stars {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: #000 url(https://eud3.oss-cn-hangzhou.aliyuncs.com/libs/ossnewyear/img/stars.png) repeat top center;
    z-index: -3;
}

/* Twinkling */
.twinkling {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: transparent url(https://eud3.oss-cn-hangzhou.aliyuncs.com/libs/ossnewyear/img/twinkling.png) repeat top center;
    z-index: -2;
    animation: move-twink-back 200s linear infinite;
}

/* Clouds */
.clouds {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: transparent url(https://eud3.oss-cn-hangzhou.aliyuncs.com/libs/ossnewyear/img/clouds3.png) repeat top center;
    z-index: -1;
    opacity: 0.4;
    animation: move-clouds-back 200s linear infinite;
}