Parallax CSS
http://www.w3schools.com/howto/howto_css_parallax.asp
.parallax {
/* The image used */
background-image: url("img_parallax.jpg");
/* Set a specific height */
height: 500px;
/* Create the parallax scrolling effect */
background-attachment: fixed;
background-position: center;
background-repeat: no-repeat;
background-size: cover;
}