border:redius:左上 右上 右下 左下;
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style type="text/css" media="screen">
.box1
{
width:150px;
height:45px;
border:1px solid blue;
box-shadow: 1px 1px 1px 1px lightblue;
border-radius: 10px 10px 10px 10px;
margin-bottom: 60px;
}
.box2
{
width:150px;
height:45px;
border:1px solid blue;
box-shadow: 1px 1px 1px 1px lightblue;
border-radius: 20px 20px 20px 20px;
margin-bottom:60px;
}
.box3
{
width:150px;
height:45px;
border:1px solid blue;
box-shadow: 1px 1px 1px 1px lightblue;
border-radius: 0 20px 0 0;
margin-bottom: 60px;
}
.box4
{
width:150px;
height:45px;
border:1px solid blue;
box-shadow: 1px 1px 1px 1px lightblue;
border-radius: 50px;
margin-bottom: 60px;
}
.box5
{
width:45px;
height:45px;
border:1px solid blue;
box-shadow: 1px 1px 1px 1px lightblue;
border-radius:50px;
}
</style>
</head>
<body>
<div class="box1">
</div>
<div class="box2">
</div>
<div class="box3">
</div>
<div class="box4">
</div>
<div class="box5">
</div>
</html>
来源：https://www.cnblogs.com/juansilence/p/6534229.html