@import url('https://fonts.googleapis.com/css?family=Exo:400,700');

*{
    margin: 0px;
    padding: 0px;
}
footer{
   background: #121212;
}
.area {
    background: #484E55;
    background: -webkit-linear-gradient(to left, #8f94fb, #484E55);
}
.area .card {
    background: #232E37;
}
.area .btn-shadow {
    -webkit-box-shadow: #2E393F 0 10px 18px !important;
    box-shadow: #2E393F 0 10px 18px !important;
}
#content{
    position: relative; //必须设为relative，小方块才能显示
}
.circles{
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    z-index: -1;
}

.circles li{
    position: absolute;
    display: block;
    list-style: none;
    width: 20px;
    height: 20px;
    background: rgba(255, 255, 255, 0.2);
    animation: animate 25s linear infinite;
    bottom: -150px;

}

.circles li:nth-child(1){
    left: 25%;
    width: 80px;
    height: 80px;
    animation-delay: 0s;
}


.circles li:nth-child(2){
    left: 10%;
    width: 20px;
    height: 20px;
    animation-delay: 2s;
    animation-duration: 12s;
}

.circles li:nth-child(3){
    left: 70%;
    width: 20px;
    height: 20px;
    animation-delay: 4s;
}

.circles li:nth-child(4){
    left: 40%;
    width: 60px;
    height: 60px;
    animation-delay: 0s;
    animation-duration: 18s;
}

.circles li:nth-child(5){
    left: 65%;
    width: 20px;
    height: 20px;
    animation-delay: 0s;
}

.circles li:nth-child(6){
    left: 75%;
    width: 110px;
    height: 110px;
    animation-delay: 3s;
}

.circles li:nth-child(7){
    left: 35%;
    width: 150px;
    height: 150px;
    animation-delay: 7s;
}

.circles li:nth-child(8){
    left: 50%;
    width: 25px;
    height: 25px;
    animation-delay: 15s;
    animation-duration: 45s;
}

.circles li:nth-child(9){
    left: 20%;
    width: 15px;
    height: 15px;
    animation-delay: 2s;
    animation-duration: 35s;
}

.circles li:nth-child(10){
    left: 85%;
    width: 150px;
    height: 150px;
    animation-delay: 0s;
    animation-duration: 11s;
}

.circles li:nth-child(11){
    left: 35%;
    width: 20px;
    height: 20px;
    animation-delay: 3s;
    animation-duration: 55s;
    bottom: 50px;
}
.circles li:nth-child(12){
    left: 50%;
    width: 15px;
    height: 15px;
    animation-delay: 1s;
    animation-duration: 110s;
    bottom: 150px;
}
.circles li:nth-child(13){
    left: 15%;
    width: 60px;
    height: 60px;
    animation-delay: 2s;
    animation-duration: 20s;
    top: 250px;
}


@keyframes animate {

    0%{
        transform: translateY(0) rotate(0deg);
        opacity: 1;
        border-radius: 0;
    }

    100%{
        transform: translateY(-1000px) rotate(720deg);
        opacity: 0;
        border-radius: 50%;
    }

}