代码如下

 <!-- 两个div -->
<div class="ball"></div>
<div class="ground"></div>

	.ball {
        width: 30px;
        height: 30px;
        background-color: black;
        border-radius: 50%;
        position: relative;
        left: 90px;
        animation: failing 0.5s ease-in infinite alternate;
      }
      .ground {
        width: 200px;
        height: 10px;
        background-color: black;
      }
      @keyframes failing {
        0% {
          transform: translateY(-150px) scale(1, 1);
        }
        90% {
          transform: scale(0.8, 1.2);
        }
        100% {
          transform: translateY(0) scale(1.2, 0.8);
        }
      }