.login-background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url('/img/children_wallpaper.jpg') no-repeat center center fixed;
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
    background-size: cover;
    opacity: 0.5;
    /*filter: alpha(opacity=50);*/
    filter: grayscale(1);
}