html, body {
    height: 100%;
}
                
.overlay{
    position: fixed;
    top: 0px;
    left: 0px;
    right: 0px;
    bottom: 0px;
    background-color: rgba(0, 0, 0, 0.8);

    .overlay-content {
        height: 100%;
        overflow: scroll;
    }
}
  
.background-content{
    height: 100%;
    overflow: auto;
}