.loading {
 width: 100%;
 height: 100%;
 background: rgba(0,0,0,0.3);
 position: fixed;
 top: 0;
 left: 0;
 z-index: 9999;
}

.loading img {
 width: 48px;
 height: 48px;
 position: absolute;
 top: 50%;
 left: 50%;
 margin-top: -24px;
 margin-left: -24px;
}