<div></div>

div{

    height: 48px;

    width: 80px;

    padding: 0 16px 0 32px;

    background: rgba(0,0,0,.6);

    position: relative;

    overflow: hidden;

}

div:after{

    display: block;

    content: "";

    height: 24px;

    width: 24px;

    position: absolute;

    top: 12px;

    right: -12px;

    background: #FFFFFF;

    border-radius: 50%;

}