Use the border-radius property to set all the four border-radius properties. You can try to run the following code to implement border-radius property:
Example
<html>
<head>
<style>
#rcorner {
border-radius: 25px;
background: #85C1E9;
color: white;
padding: 20px;
width: 200px;
height: 250px;
}
</style>
</head>
<body>
<p id = "rcorner">Rounded corners!</p>
</body>
</html>