#overlay {
    content: '';
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.7);
}
    #overlay .loader {
        position: relative;
        top: 50%;
        transform: translateY(-50%);
    }
    #overlay strong {
        display: inline-block;
        margin-top: 5px;
        margin-left: 10px;
        color: #fff;
    }