.loading {
    position: absolute;
    width: 100px;
    height: 100px;
    border-radius: 50%;
    border: 10px solid #ddd;
    border-top-color: orange;
    animation: loading 3s linear infinite;
    left:calc(50% - 50px);
    top:calc(50% - 50px);
    opacity: 0.3;
}
@keyframes loading {
    to {
        transform: rotate(360deg);
    }
}