请老师帮忙检查下代码写法的合理性和规范性，谢谢

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>2-2</title>
    <style type="text/css">
        div {
            font-family: 'Microsoft Yahei';
            font-size: 60px;
            font-weight: bold;
            line-height: 600px;
            position: absolute;
            top: 0;
            right: 0;
            bottom: 0;
            left: 0;
            width: 800px;
            height: 600px;
            margin: auto;
            text-align: center;
            border: 5px solid #000;
            border-radius: 50%;
            /*调用动画*/
            -webkit-animation-name: banner_animation;
                    animation-name: banner_animation;
            -webkit-animation-duration: 2s;
                    animation-duration: 2s;
       }
       /*定义动画*/
       @keyframes banner_animation{
            from{opacity: 0;}
            to{opacity: 1;}
       }
   </style>
</head>
<body>
    <div>大家好，欢迎来到慕课网！</div>
</body>
</html>

wangstudyvc 2019-07-26

源自：CSS3动画 2-6 编程练习