border-bottom-left-radius

The border-bottom-left-radius CSS property sets the rounding of the bottom-left 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.

Values

<length>
Denotes the size of the circle radius or the semi-major and semi-minor axes of the ellipsis. It can be expressed in any unit allowed by the CSS <length> data types. Negative values are invalid.
<percentage>
Denotes the size of the circle radius, or the semi-major and semi-minor axes of the ellipsis, using percentage values. Percentages for the horizontal axe refer to the width of the box, percentages for the vertical axe refer to the height of the box. Negative values are invalid.

Example

<!DOCTYPE HTML>
<html>
    <head>
        <title>CSS Tutorials</title>
        <style>
            div {
                border-bottom-left-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 left radius
        </div>
    </body>
</html>