html + css 实现小球跳动动画

具体步骤是：

定义一个大盒子 box，b o x–content 代表小球，circle代表小洞。。

    &lt;div class="box"&gt;
        &lt;div class="box-content left"&gt;&lt;/div&gt;
        &lt;div class="circle left1"&gt;&lt;/div&gt; 
    </div&gt;

2. 设置外层盒子的样式，采用 display 属性，以列的形式进行排序。。

内部元素位置为底部对齐

      .box {
            width: 100px;
            height: 300px;
            /* border: 1px solid #000; */
            margin:0 auto;
            display: flex;
            flex-direction: column;
            justify-content: flex-end;
            align-items: center;
        }

3. 设置小球样式，宽高各为50px，边框弧度为百分之50，背景颜色为渐变色，

     .box-content {
            width: 50px;
            height: 50px;
            /* border: 1px solid #000; */
            border-radius: 50%;
            /* margin: 20px auto; */
            background: linear-gradient(0deg,blue,red);
            box-shadow: 0 0 5px  rgba(0,0,0,0.5);
            animation: animal 2s infinite alternate linear;
      }

4.设置 circle 样式，

.circle{
            width: 50px;
            height: 10px;
            background-color: rgba(0,0,0,0.5);
            border-radius: 50%;
            animation: animal1 2s infinite alternate linear;
}

5.设置动画效果，

        /* 小洞的动画效果 */
        @keyframes animal1 {
              0% {
                 transform: scale(1.2);
              }
              100% {
                transform: scale(0.5);
              }
        }
        /*小球的动画效果 */
        @keyframes animal {
            0% {
                transform: translateY(0);
            }
            100% {
                transform: translateY(-250px);
            }
        }

效果如下：

全部代码如下：

<!DOCTYPE html&gt;
<html lang="en"&gt;
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        body {
            width: 100vw;
            height: 100vh;
            display: flex;
            /* justify-content: flex-end; */
            justify-content: center;
            align-items: center;
        }
        .box {
            width: 100px;
            height: 300px;
            /* border: 1px solid #000; */
            margin:0 auto;
            display: flex;
            flex-direction: column;
            justify-content: flex-end;
            align-items: center;
        }
        .box-content {
            width: 50px;
            height: 50px;
            /* border: 1px solid #000; */
            border-radius: 50%;
            /* margin: 20px auto; */
            background: linear-gradient(0deg,blue,red);
            box-shadow: 0 0 5px  rgba(0,0,0,0.5);
            animation: animal 2s infinite alternate linear;
        }
        
        .box .left {
            background: linear-gradient(0deg,rgb(0, 255, 170),rgb(0, 162, 255));
            animation-duration: 800ms;
        }
        .box .left1 {
            animation-duration: 800ms;
        }
        .box .right {
            background: linear-gradient(0deg,rgb(208, 255, 0),rgb(255, 0, 230));
            animation-duration: 1s;
            /* animation-delay: 50ms; */
        }
        .box .right1 {
             animation-duration: 1s;
        }
        .circle{
            width: 50px;
            height: 10px;
            background-color: rgba(0,0,0,0.5);
             border-radius: 50%;
             animation: animal1 2s infinite alternate linear;
        }
        /* 小洞的动画效果 */
        @keyframes animal1 {
              0% {
                 transform: scale(1.2);
              }
              100% {
                transform: scale(0.5);
              }
        }
        /*小球的动画效果 */
        @keyframes animal {
            0% {
                transform: translateY(0);
            }
            100% {
                transform: translateY(-250px);
            }
        }
    </style>
</head>
<body>
    <div class="box">
        <div class="box-content left"></div>
        <div class="circle left1"></div> 
    </div>
    <div class="box">
        <div class="box-content"></div>
        <div class="circle"></div>
    </div>
    <div class="box">
        <div class="box-content right"></div>
        <div class="circle right1"></div>  
    </div>
</body>
</html>