效果展示：
源码：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>(?????)圆角边框</title>
<style>
#div1{
width:100px;
height: 100px;
border: 10px solid red;
border-radius: 100px ;
}
text{
font-size: 30px;
color: red;
}
#nav{
width: 100px;
display: flex;
align-items: center;
justify-content: space-around;
height: 100px;
}
</style>
</head>
<body>
<div id="div1">
<div id="nav">
<div>
<text>?</text>
<text>?</text>
<text>?</text>
</div>
</div>
<h2></h2>
</div>
</body>
</html>