<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<div class="top-box">
<div class="top-box-inner"></div>
</div>
</body>
<style>
* {
padding: 0;
margin: 0;
}
.top-box {
overflow: hidden;
}
.top-box-inner {
position: relative;
width: 100%;
height: 200px;
}
.top-box-inner:after {
width: 140%;
height: 200px;
position: absolute;
left: -20%;
top: 0;
z-index: -1;
content: '';
border-radius: 0 0 50% 50%;
background-color: #000000;
}
</style>
</html>
