请老师检查，有可以优化的地方吗

相关代码：

<!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>Document</title>
    <style>
        .box1,.box2{
            width: 800px;
            height: 300px;
            border: 1px solid #000;
            overflow: hidden;
        }
        div .jianbian{
            border-radius: 50%;
            width: 800px;
            height: 800px;
            background-image:radial-gradient(50% 50%, white 0,white 60%,orange 60%,orange 68%,yellow 68%,yellow 76%,green 76%,green 84%,blue 84%,blue 92%,purple 92%,purple 100%);
        }
        .box2 {
            position: relative;
        }
        .box2 div{
            border: 20px solid #000;
            border-radius: 50%;
            margin: 0 auto;
            overflow: hidden;
            position: absolute;
        }
        .box2 .radius1{
            width: 760px;
            height: 760px;
           border-color:purple ;
        }
        .box2 .radius2{
            top: 20px;
            left: 20px;
            width:720px;
            height:720px;
            border-color:blue;
        }
        .box2 .radius3{
            top: 40px;
            left: 40px;
            width:680px;
            height:680px;
            border-color:green;        
        }
        .box2 .radius4{
            top: 60px;
            left: 60px;
            width:640px;
            height:640px;
            border-color:yellow;        
        }
        .box2 .radius5{
            top: 80px;
            left: 80px;
            width:600px;
            height:600px;
            border-color:orange;
        }

    </style>
</head>
<body>
    <div class="box1">
        <div class="jianbian"></div>
    </div>
    <div class="box2">
        <div class="radius1"></div>
        <div class="radius2"></div>
        <div class="radius3"></div>
        <div class="radius4"></div>
        <div class="radius5"></div>
    </div>
</body>
</html>

迷迷糊糊学习 2021-11-30

源自：背景与渐变 2-28 项目作业