.fan-wrapper {
    overflow: hidden;
    position: relative;
    margin: 200px;
    width: 400px;
    height: 400px;
    border-radius: 50%;
    background: radial-gradient(circle, darkgrey, grey)
}

.fan {
    position: absolute;
    right: 0;
    animation: rotateAnimate 2s linear infinite;
    /* 这一行很重要，设置左下角为旋转点 */
    transform-origin: 0% 100%;
    width: 200px;
    height: 200px;
    /*background: darkgrey;*/
    background: radial-gradient(circle, grey, darkgrey)
}