.overlay {
    /* Height & width depends on how you want to reveal the overlay (see JS below) */   
    height: 100%;
    width: 0;
    position: fixed; /* Stay in place */
    z-index: 1; /* Sit on top */
    left: 0;
    top: 0;
    background-color: rgb(0,0,0); /* Black fallback color */
    background-color: rgba(0,0,0, 0.9); /* Black w/opacity */
    overflow-x: hidden; /* Disable horizontal scroll */
    transition: 0.5s; /* 0.5 second transition effect to slide in or slide down the overlay (height or width, depending on reveal) */
  }
.popup{
    width: 300px;
    background: #fff;
    border-radius: 6px;
    position: absolute;
    top: 0;
    left: 50%;
    transform: translate(-50%,-50%) scale(0.1);
    text-align: center;
    padding: 0 30px 30px;
    color: #333;
    visibility: hidden;
    transition: transform 0.4s, top 0.4s;
}
.open-popup{
    position: fixed;
    visibility: visible;
    top: 50%;
    transform: translate(-50%,-50%) scale(1);    
}
.popup img{
    width: 100px;
    margin-top: -50px;
    border-radius: 50%;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
}
.popup h2{
    font-size: 38px;
    font-weight: 500;
    margin: 30px 0 10px;
}
.popup button{
    width: 100%;
    margin-top: 50px;
    padding: 10px 0;
    background: #6fd649;
    color: #fff;
    border: 0;
    outline: none;
    font-size: 18px;
    border-radius: 4px;
    cursor: pointer;
    box-shadow: 0 5px 5px rgba(0, 0, 0, 0.2);
}