html {
    background-color:#424242;
}

div.center-on-page {
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
}

.lds-dual-ring {
    display: inline-block;
    width: 64px;
    height: 64px;
    width: 100%;
    height: 100%;
}

.lds-dual-ring:after {
    content: " ";
    display: block;
    width: 46px;
    height: 46px;
    margin: 1px;
    border-radius: 50%;
    border: 5px solid #FFF;
    border-color: #FFF transparent #FFF transparent;
    animation: lds-dual-ring 1.2s linear infinite;
}

@keyframes lds-dual-ring {
    0% {
        transform: rotate(0deg);
    }

    100% {
        transform: rotate(360deg);
    }
}