negative border radius inverted code example

Example 1: css inverted border radius

.class-to-apply-to:before {
   box-shadow: 0 20px 0 0 #522d5b;
}

Example 2: negative border radius

.player {
    width: 480px;
    height: 80px;
    border-radius:0 40px 40px 0;
    background-color:#0000FF;
    position:relative;    
    color:#FFF;
}

.player:before
{
    width: 80px;
    height: 80px;
    border-radius:0 40px 40px 0;
    background-color:#FFF;    
    display:inline-block;
    vertical-align: middle;
    margin-right: 10px;
    content: '';
}