/* SET */

header {
    background-color: #000;
    background-image: url("background.png");
	background-size: max(756px, 100%);
	background-position: center;
    animation: background 20s ease-in-out infinite;
    opacity: 1;
}

body > img { /* Logo placement */
    margin: 200px auto;
}

/* ANIMATED */

@keyframes background {
    0%, 100% {background-size:max(756px, 100%); }
    50% {background-size: max(800px, 110%); }
}