.loader {
    width: 80px;
    height: 80px;
    position:fixed;
    top: 50%;
    left: 50%;
    margin-top: -40px; /*set to a negative number 1/2 of your height*/
    margin-left: -40px; /*set to a negative number 1/2 of your width*/
    z-index: 9999;
}
.loader div {
    position: absolute;
    border: 4px solid #006aff;
    opacity: 1;
    border-radius: 50%;
    animation: loader 1s cubic-bezier(0, 0.2, 0.8, 1) infinite;
}
.loader div:nth-child(2) {
    animation-delay: -0.5s;
}
@keyframes loader {
    0% {
    top: 36px;
    left: 36px;
    width: 0;
    height: 0;
    opacity: 1;
    }
    100% {
    top: 0px;
    left: 0px;
    width: 72px;
    height: 72px;
    opacity: 0;
    }
}