<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>边界圆角</title>
<style>
.box {
width: 300px;
height: 300px;
background-color: orangered;
}
.box {
/*固定值 | 百分比*/
/*border-radius: 10%;*/
/*左上为第一个角，顺时针编号*/
/*border-radius: 10px 20px 30px 40px;*/
/*不足找对角*/
/*border-radius: 10px 50px 100px;*/
/*border-radius: 10px 50px;*/
/*横纵分离,先横后纵*/
/*border-radius: 50px / 50%;*/
/*border-radius: 50px 100px / 50%;*/
border-radius: 60%;
}
</style>
<style>
.b {
width: 300px;
height: 150px;
background-color: orangered;
border-radius: 50% 50% 0 0 / 100% 100% 0 0;
}
</style>
</head>
<body>
<div class="box"></div>
<div class="b"></div>
</body>
</html>原文：https://www.cnblogs.com/bladecheng/p/11284506.html