效果：
源码：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>(?????)圆角边框</title>
<style>
#div1{
width:100px;
height: 100px;
margin: 30px;
border: 10px solid red;
border-radius: 0 100px 0 0;
}
img{
border-radius: 171px;
}
</style>
</head>
<body>
<div id="div1">
</div>
<img src="images/title.png" >
</body>
</html>
原文：https://www.cnblogs.com/zhuhukang/p/15078807.html