.preloader {
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: #666666;
    opacity: 0.8;

    position: fixed;
    width: 100%;
    height: 100%;
    left: 0;
    right: 0;
    top: 0;
    bottom: 0;
    z-index: 9999;
}

.lds-grid img {
    display: inline-block;
    position: relative;
    width: 80px;
    height: 80px;
    animation-name: spin;
    animation-duration: 4000ms;
    animation-iteration-count: infinite;
    animation-timing-function: linear;
}

@keyframes spin {
    from {
        transform: rotate(0deg);
    }

    to {
        transform: rotate(360deg);
    }
}