Line bounce CSS

selector:after {
    content: '';
    display: block;
    position: absolute;
    border: 1px solid #fff;
    left: -20px;
    right: -20px;
    top: -20px;
    bottom: -20px;
    border-radius: 50%;
    animation: line-bounce 1.5s linear infinite;
    opacity: 0;
    backface-visibility: hidden;
}