body {
    background: #000;
}

.loading {
    background-image: url('/Content/images/spinner.gif');
    background-repeat: no-repeat;
    width: 39px;
    height: 39px;
    margin: auto;
    position: fixed;
    top: 50%;
    left: 50%;
    -webkit-transform: translate(-50%, -50%);
    transform: translate(-50%, -50%);
}