.inverted-radius-wrapper:before {
    content: '';
    display: block;
    width: 40px;
    height: 25px;
    background-color: transparent;
    border-radius: 0 0 0 25px;
    box-shadow: calc(15px * -0.5) calc(15px * 0.5) 0 0 #f9f9f9;
    position: absolute;
    z-index: -1;
    left: -1px;
    bottom: 100%;
}
.inverted-radius-wrapper:after {
    content: '';
    display: block;
    width: 40px;
    height: 25px;
    background-color: transparent;
    border-radius: 0 0 0 25px;
    box-shadow: calc(15px * -0.5) calc(15px * 0.5) 0 0 #f9f9f9;
    position: absolute;
    z-index: -1;
    left: calc(100% - 1px);
    bottom: 0;
}