<!DOCTYPE html>
<html>
<head>
<style>
div {
    border: 2px solid;
    padding: 10px;
    background: #dddddd;
    border-top-right-radius: 2em;
}

</style>
</head>
<body>

<div>The border-top-right-radius property allows you to add a rounded border to the top-right corner.</div>

</body>
</html>