.black-screen{
    position: fixed;
    background-color: rgba(0,0,0,.75);
    bottom: 0;
    right: 0;
    opacity: 0;
    transition: opacity .3s ease,z-index .01s ease ;
    z-index: -1;
    width: 100%;
    height: 100%;
    overflow: hidden;
}
.black-screen-active{
    opacity: 1;
    z-index: 40;
}