body{
  padding: 100px 0;
}
#fondo{
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: #006392;
    background-image: url('https://images.unsplash.com/photo-1510434642308-ae5fec689403?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=1963&q=80');
    background-position: center;
    background-size: cover;
    animation-name: bg-zoom;
    animation-duration: 50s;
    animation-iteration-count: infinite;
    animation-direction: alternate;
    z-index: -1;
}
@keyframes bg-zoom{
    100% { transform: scale(1.1); }
}