<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Свойсто border-radius</title>
<style type="text/css">
#a, #b ,#c {
width: 150px;
height: 150px;
position: absolute;
padding: 10px 20px;
}
#a {
border-radius: 0 50%;
background-color: #9999FF;
left: 50px;
top: 50px;
color: white;
}
#b {
border-radius: 50% 0;
background-color: #99FF99;
left: 100px;
top: 100px;
text-align: right;
}
#c {
background-color: #FF9999;
left: 150px;
top: 150px;
border-radius: 50%;
text-align: center;
color: white;
}
</style>
</head>
<body>
<div id="a">Слой №1<br />border-radius: 0 50%;</div>
<div id="b">Слой №2<br />border-radius: 50% 0;</div>
<div id="c">Слой №3<br />
border-radius: 50%;</div>
</body>
</html>