@keyframes slider {
    from {
        background-image: url('../images/dark_tint.png'), url('../images/pizza-banner-0.jpg');
    }
    50% {
        background-image: url('../images/dark_tint.png'), url('../images/pizza-banner-1.jpg');
    }
    to {
        background-image: url('../images/dark_tint.png'), url('../images/pizza-banner-2.jpg');
    }
}