Three Rounding Values for Different Corners in CSS
If three values are specified, the first value specifies the rounding for the upper left corner, the second for both the upper right and lower left corners, and the third for the lower right corner:
<div id="elem"></div>
#elem {
width: 300px;
height: 100px;
border: 1px solid red;
border-radius: 10px 20px 30px;
}
:
