.popup{
    position: absolute;
    top:50%;
    left: 50%;
    width:600px;
    height:500px;
    margin-left:-300px;
    margin-top:-250px;
    border-radius:20px;
    background-color: white;
    visibility: hidden;
    transition: 1s;
    overflow: hidden;
}

.popup-active{
    visibility: visible;
}