.taiJi {
    background: #fff;
    width: 100px;
    height: 50px;
    border-color: #000;
    border-style: solid;
    border-width: 2px 2px 50px 2px;
    border-radius: 100%;
    position: relative;
    margin: 0 auto;
  }
  
  .taiJi:before {
    content: "";
    position: absolute;
    top: 50%;
    left: 0;
    border: 19px solid #000;
    border-radius: 100%;
    width: 12px;
    height: 12px;
    background: #fff;
  }
  
  .taiJi:after {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    border: 19px solid #fff;
    border-radius: 100%;
    width: 12px;
    height: 12px;
    background: #000;
  }