*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body {
    background-color: #242424;
    width: 100%;
    height: 100vh;
    position: relative;
}
span{
    border-radius: 50%;
    transform: translate(-50%,-50%);
    animation: anim 1s linear;
}
@keyframes anim {
    0% {
        width: 0;
        height: 0;
        border: 2px solid #fff ;
    }
    100%{
        width: 100px;
        height: 100px;
        border: 2px solid rgba(255,255,255,0);
    }
}