CSS Fade In Effect

div {
    animation: fadein 1s;
    -moz-animation: fadein 3s; /* Firefox */
    -webkit-animation: fadein 3s; /* Safari and Chrome */
    -o-animation: fadein 3s; /* Opera */
}

@keyframes fadein {
    from {
        opacity:0;
    }
    to {
        opacity:1;
    }
}