.box-taiji {
    width: 0;
    height: 400px;
    position: relative;
    margin: 50px auto;
    border-left: 200px solid #000;
    border-right: 200px solid #fff;
    box-shadow: 0 0 30px rgba(0,0,0,.5);
    border-radius: 400px;
    animation: rotation 2.5s linear infinite;
    -webkit-animation: rotation 2.5s linear infinite;
    -moz-animation: rotation 2.5s linear infinite;
}

    .box-taiji:before,
    .box-taiji:after {
        position: absolute;
        content: "";
        display: block;
    }

    .box-taiji:before {
        width: 200px;
        height: 200px;
        top: 0;
        left: -100px;
        z-index: 1;
        background-color: #fff;
        border-radius: 50%;
        box-shadow: 0 200px 0 #000;
    }

    .box-taiji:after {
        width: 60px;
        height: 60px;
        top: 70px;
        left: -30px;
        z-index: 2;
        background-color: #000;
        border-radius: 50%;
        box-shadow: 0 200px 0 #fff;
    }

@keyframes rotation {
    0% {
        transform: rotate(0deg);
    }

    100% {
        transform: rotate(-360deg);
    }
}

@-webkit-keyframes rotation {
    0% {
        -webkit-transform: rotate(0deg);
    }

    100% {
        -webkit-transform: rotate(-360deg);
    }
}

@-moz-keyframes rotation {
    0% {
        -moz-transform: rotate(0deg);
    }

    100% {
        -moz-transform: rotate(-360deg);
    }
}