老师看一下这样写对吗

来源：2-18 编程练习

一心励志当码农

2021-04-29 17:21:05

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>2-9</title>
    <style type="text/css">
        div {
            font-family: Arial;
            font-size: 72px;
            font-weight: bold;
            position: fixed;
            right: 0;
            left: 0;
            width: 30px;
            height: 30px;
            bottom: 30px;
            margin: auto;
            transform: rotate(90deg);
            /*此处写代码*/
            animation: r 1s linear 0.5s alternate infinite;

        }

        @keyframes r {
            from {
                bottom: 30px;
            }

            to {
                bottom: 10px;
            }
        }
    </style>
</head>

<body>
    <div>&gt;</div>
</body>

</html>