.popup-tutorial
{
    position: absolute;
    margin-left: 50vw;
    margin-top: 50vh;
    width: 600px;
    height: 200px;
    background: white;
    box-shadow: 0 0 10px gray;
    border-radius: 3px;
    transform: translate(-50%, -50%);
    padding: 25px;
}

.popup-tutorial h4
{
    text-align: center;
}