<!DOCTYPE HTML>
<head>
	<style>
		.parent {
		  width: 200px;
		  height: 200px;
		  overflow: hidden;
			border-radius: 0px 0px 20px 0px;

			position: absolute;
			z-index: 0;
			background-color: #00ff00;
		}

		.child {
		  width: 300px;
		  height: 300px;
		  margin-left: 100px;
		  background-color: #ffff00;
		}

		body {
			margin: 0;
		}

	</style>
</head>
<body>
	<div class="parent">
	    <div class="child"></div>
	</div>
</body>