body{margin:0;padding:0}body,html{height:100%;margin:0;padding:0;overflow:hidden}.background-image{width:100%;height:100%;position:absolute}.overlay{width:100%;height:100%;display:flex;position:absolute}.left,.right{cursor:pointer;flex:1}.popup{color:#fff;background:#000c;border-radius:10px;padding:20px;display:none;position:fixed;top:50%;left:50%;transform:translate(-50%,-50%)}.popup.active{display:block}