*{
    /* 初始化 */
    margin: 0;
    padding: 0;
}
body{
    /* 100%窗口高度 */
    height: 100vh;
    /* 弹性布局 居中 */
    display: flex;
    justify-content: center;
    align-items: center;
    /* 渐变背景 */
    background: #a1c4fd;  /* fallback for old browsers */
    background: -webkit-linear-gradient(to right, #a1c4fd, #c2e9fb);  /* Chrome 10-25, Safari 5.1-6 */
    background-image: linear-gradient(120deg, #a1c4fd, #c2e9fb); /* W3C, IE 10+/ Edge, Firefox 16+, Chrome 26+, Opera 12+, Safari 7+ */

    /* 溢出隐藏 */
    overflow: hidden;
}
.block li{
    position: absolute;
    border: 1px solid #fff;
    background-color: #fff;
    width: 30px;
    height: 30px;
    list-style: none;
    opacity: 0;
}
.square li{
    top: 40vh;
    left: 60vw;
    /* 执行动画：动画名 时长 线性的 无限次播放 */
    animation: square 10s linear infinite;
}
.square li:nth-child(2){
    top: 80vh;
    left: 10vw;
    /* 设置动画延迟时间 */
    animation-delay: 2s;
}
.square li:nth-child(3){
    top: 80vh;
    left: 85vw;
    /* 设置动画延迟时间 */
    animation-delay: 4s;
}
.square li:nth-child(4){
    top: 10vh;
    left: 70vw;
    /* 设置动画延迟时间 */
    animation-delay: 6s;
}
.square li:nth-child(5){
    top: 10vh;
    left: 10vw;
    /* 设置动画延迟时间 */
    animation-delay: 8s;
}
.circle li{
    bottom: 0;
    left: 15vw;
    /* 执行动画 */
    animation: circle 10s linear infinite;
}
.circle li:nth-child(2){
    left: 35vw;
    /* 设置动画延迟时间 */
    animation-delay: 2s;
}
.circle li:nth-child(3){
    left: 55vw;
    /* 设置动画延迟时间 */
    animation-delay: 6s;
}
.circle li:nth-child(4){
    left: 75vw;
    /* 设置动画延迟时间 */
    animation-delay: 4s;
}
.circle li:nth-child(5){
    left: 90vw;
    /* 设置动画延迟时间 */
    animation-delay: 8s;
}

/* 定义动画 */
@keyframes square {
    0%{
        transform: scale(0) rotateY(0deg);
        opacity: 1;
    }
    100%{
        transform: scale(5) rotateY(1000deg);
        opacity: 0;
    }
}
@keyframes circle {
    0%{
        transform: scale(0) rotateY(0deg);
        opacity: 1;
        bottom: 0;
        border-radius: 0;
    }
    100%{
        transform: scale(5) rotateY(1000deg);
        opacity: 0;
        bottom: 90vh;
        border-radius: 50%;
    }
}