Positioned on the background css code example
Example 1: move css background image
background-image: url('w3css.gif');
background-repeat: no-repeat;
background-attachment: fixed;
background-position: center;
Example 2: css image background center horizontally in div
/*
div with
class="slot_image"
*/
.slot_image{
background: url(url) no-repeat center;
}