<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<style>
#div1{width:200px; height:200px; background:red; border-radius:50%;}
#div2{width:200px; height:200px; background:red;
border-radius:1em;/*单位*/
}
#div3{width:200px; height:200px; background:red;
border-radius:10px 30px 50px 100px;
/*左上 右上 右下 左下*/
}
</style>
</head>
<body>
<div id="div1"></div>
<div id="div2"></div>
<div id="div3"></div>
</body>
</html>
