div#loadingDiv {
    top: 50%;
    left: 50%;
    position: absolute;
    transform: translate(-50%, -50%);
}

    div#loadingDiv > div.loader {
        border: 5px solid #f3f3f3;
        border-radius: 50%;
        border-top: 5px solid #555;
        width: 45px;
        height: 45px;
        -webkit-animation: spin 2s linear infinite; /* Safari */
        animation: spin 0.8s linear infinite;
        margin: auto;
    }

    div#loadingDiv > div.message {
        font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        font-size: 14px;
        font-weight: 500;
        margin-top: 20px;
    }

/* Safari */
@-webkit-keyframes spin {
    0% {
        -webkit-transform: rotate(0deg);
    }

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

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

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