.center-fade {
    display: block;
    margin-left: auto;
    margin-right: auto;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    opacity: 0;
    animation: fadeIn 4s forwards;
}

@keyframes fadeIn {
    to {
        opacity: 1;
    }
}