* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}
body
{
    display:flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: black;
}
.container
{
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
}
.container .box
{
    width: 500px;
    height: 500px;
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 50px 0;
}
.container .box span
{
    position: absolute;
    box-sizing: border-box;
    border: 2px solid white;
    border-radius: 50%;
    animation: animate 5s linear infinite;
    animation-delay: calc(-0.5s * var(--i));
}

@keyframes animate
{
    0%
    {
        width: 0px;
        height: 0px;
    }
    50%
    {
        opacity: 1;
    }
    100%
    {
        width: 800px;
        height: 400px;
        opacity: 0;
    }
}
.container .box {
    animation: pulse 1s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.1); }
}