Four Rounding Values for Different CSS Corners
If four values are specified, the first value specifies the rounding for the upper-left corner, the second for the upper-right corner, the third for the lower-right corner, and the fourth for the lower-left corner:
<div id="elem"></div>
#elem {
width: 300px;
height: 100px;
border: 1px solid red;
border-radius: 10px 20px 30px 40px;
}
:
