Checkout this example:
#content {
height: 300px;
text-align: center;
font-size: 26px;
color: #000;
position:relative;
}
.bg{
position: absolute;
left: 0;
right: 0;
top: 0;
bottom: 0;
z-index: -1;
background: url(http://www.gstatic.com/webp/gallery/1.jpg) 0% 0% repeat;
animation-name: MOVE-BG;
animation-duration: 100s;
animation-timing-function: linear;
animation-iteration-count: infinite;
}
@keyframes MOVE-BG {
from {
transform: translateX(0);
}
to {
transform: translateX(-187%);
}
}
<div id="content">Foreground content
<div class="bg"></div>
</div>