#header:before {
    background: url(%%header%%) no-repeat center top;
    height: 50px;
    content: '';
    position: absolute;
    top: 19px;
    right: 0;
    bottom: 0;
    left: 0;
    z-index: -1;
    -webkit-animation: pan 10s linear infinite;
    -moz-animation: pan 10s linear infinite;
    animation: pan 10s linear infinite;
}
@-webkit-keyframes pan {
    0%   { background-position: 50% 0; }
    50%  { background-position: 50% -800px; }
    100% { background-position: 50% 0; }
}
@-moz-keyframes pan {
    0%   { background-position: 50% 0; }
    50%  { background-position: 50% -800px; }
    100% { background-position: 50% 0; }
}
@keyframes pan {
    0%   { background-position: 50% 0; }
    50%  { background-position: 50% -800px; }
    100% { background-position: 50% 0; }
}