Circle waiting

HTML

<div class="major">
    <div class="minor"></div>
    <div class="mask"></div>
</div>

CSS

.major {
    background-color: #008000;
    width: 100px;
    height: 100px;
    border-radius: 50px;
    position: relative;
    -webkit-animation: rotating 1s linear infinite;
}
.minor {
    background: -webkit-radial-gradient(center, ellipse cover, #fff 0%, #008000 100%);
    width: 25px;
    height: 25px;
    border-radius: 12.5px;
    position: absolute;
    top: 0;
    left: 37.5px;
}
.mask {
    width: 50px;
    height: 50px;
    border-radius: 25px;
    background-color: #fff;
    position: absolute;
    top: 25px;
    left: 25px;
}
.major:nth-child(2) .minor {
    top: 25px;
    left: 0;
}
@-webkit-keyframes rotating {
    from {
        -webkit-transform: rotate(0deg);
    }
    to {
        -webkit-transform: rotate(360deg);
    }
}