.loader {
    position: relative;
}
.loader:before {
    content: "";
    animation: block-loader-rotate 1s linear infinite;
    border: 5px solid #ececec;
    border-top-color: #359ae3;
    border-radius: 50%;
    display: block;
    height: 3.125rem;
    left: calc(50% - 1.5625rem);
    position: absolute;
    top: calc(50% - 1.5625rem);
    width: 3.125rem;
    z-index: 5;
}
.loader:after {
    background-color: rgba(255, 255, 255, 0.5);
    content: "";
    display: block;
    height: 100%;
    left: 0;
    position: absolute;
    top: 0;
    width: 100%;
    z-index: 4;
}
@keyframes block-loader-rotate {
    0% {
        transform: rotate(0);
    }
    100% {
        transform: rotate(360deg);
    }
}