* {
    margin: 0;
    padding: 0;
}

body {
    background-color: #ccc;
}

.taiji {
    width: 150px;
    height: 300px;
    margin: 100px auto;
    border-right: 150px solid #000;
    background-color: #fff;
    border-radius: 150px;
    animation: rotate 2s infinite linear;
}

.taiji::before,
.taiji::after {
    content: '';
    margin-left: 50%;
    display: block;
    width: 50px;
    height: 50px;
    background-color: #fff;
    border: 50px solid #000;
    border-radius: 75px;
}

.taiji::after {
    background-color: #000;
    border: 50px solid #fff;
}

@keyframes rotate {
    from {}

    to {
        transform: rotate(-360deg);
    }
}