<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
.block{
background:skyblue;
height:60px;
width:60px;
position: relative;
border-radius: 10px;
}
.block:before{
border-top-right-radius: 60px;
background: white;
position: absolute;
left: 0;
bottom: 0;
content: '';
display: block;
width: 20px;
height: 20px;
}
.block:after{
border-bottom-left-radius: 60px;
background: white;
position: absolute;
right: 0;
top: 0;
content: '';
display: block;
width: 20px;
height: 20px;
}
</style>
</head>
<body>
<div class="block"></div>
</body>
</html>
