1. html 结构
<!DOCTYPE html>
<html lang="en">
<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>transition</title>
</head>
<body>
  <div class="box"></div>
</body>
</html>
 
2. css 样式
body {
      background-color: #333;
      display: flex;
      justify-content: center;
      align-items: center;
      height: 100vh;
    }
    .box {
     background-color: white;
     width: 100px;
     height: 100px;
     /* transition-property: background; */
     /* transition-duration: 2s; */
     /* 延迟 */
     /* transition-delay: 2s; */
     /* transition-timing-function: ease-in-out; */
     transition: 2s ease-in-out;
    }
    .box:hover {
      background-color: red;
      border-radius: 50%;
      width: 300px;
      height: 300px;
    }
 
3. 动画属性
transition: 2s ease-in-out;