.overlay{
    background-image: url(https://img.freepik.com/free-vector/fantasy-galaxy-holographic-background-pastel-colors_126980-86.jp?size=626&ext=jpg);
    background-size: 100%;
    background-repeat: no-repeat;
    position:absolute;
    top: 0vw;
    left: 0vw;
    width: 100%;
    height: 100%;
    left: vw;
    z-index: 1;
    opacity: 0.9;
}