SOURCE

<div class="container">
    <div class="wave"></div>
</div>

.wave {
    position: relative;
    width: 200px;
    height: 200px;
    background-color: rgb(118, 218, 255);
    border-radius: 50%;
 
    &::before,
    &::after{
        content: "";
        position: absolute;
        width: 400px;
        height: 400px;
        top: 0;
        left: 50%;
        background-color: rgba(255, 255, 255, .4);
        border-radius: 45%;
        transform: translate(-50%, -70%);
        animation: rotate 6s linear infinite;
        z-index: 10;
    }
    
    &::after {
        border-radius: 47%;
        background-color: rgba(255, 255, 255, .9);
        transform: translate(-50%, -70%) rotate(0);
        animation: rotate 10s linear -5s infinite;
        z-index: 20;
    }
}

@keyframes rotate {
    50% {
        transform: translate(-50%, -73%) rotate(180deg);
    } 100% {
        transform: translate(-50%, -70%) rotate(360deg);
    }
}