.loader {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 10000;
    background: rgba(255, 255, 255, .5);
    color: #ffffff;
    text-align: center;
    font-size: 30px;
    display: none;
}

.loader.active {
    display: block;
}