.spinner {
    display: none;
    position: fixed;
    z-index: 100;
    width: 100%;
    height: 100%;
    background-color: rgba(192, 192, 192, 0.5);
    background-image: url('../img/loading.gif');
    background-repeat: no-repeat;
    background-position: center;
}

.center {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    margin: auto;
}

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