border-bottom-right-radius

The border-bottom-right-radius CSS property sets the rounding of the bottom-right corner of the element. The rounding can be a circle or an ellipse, or if one of the value is 0 no rounding is done and the corner is square.
 
A background, being an image or a color, is clipped at the border, even a rounded one; the exact location of the clipping is defined by the value of the background-clip property.

Example

<!DOCTYPE HTML>
<html>
    <head>
        <title>CSS Tutorials</title>
        <style>
            div {
                border-bottom-right-radius: 40%;
                border-style: black 3px double;
                background-color: rgb(250, 20, 70);
                background-clip: content-box;
                width: 200px;
				height:300px;
            }
        </style>
    </head>
    <body>
        <div>
            border bottom right radius
        </div>
    </body>
</html>