:root {
    --bg-z-index: 9999;
    --loader-size: 40px;
}

/* loader */
.loading-background{
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.5);
    z-index: var(--bg-z-index);
}
.lds-dual-ring {
    display: inline-block;
    width: calc(var(--loader-size) * 2);
    height: calc(var(--loader-size) * 2);
}
.lds-dual-ring:after {
    content: " ";
    display: block;
    width: 64px;
    height: 64px;
    margin: 8px;
    border-radius: 50%;
    border: 6px solid #fff;
    border-color: #fff transparent #fff transparent;
    animation: lds-dual-ring 1.2s linear infinite;
}
/* center */
.lds-dual-ring {
    z-index: calc(var(--bg-z-index) + 1);
    position: fixed;
    top: calc(50% - var(--loader-size));
    left: calc(50% - var(--loader-size));
}
@keyframes lds-dual-ring {
    0% {
        transform: rotate(0deg);
    }
    100% {
        transform: rotate(360deg);
    }
}