div#main{
    width: 100%;
    height:2000px;
    margin:auto;
}

body{background:url(fond-nerepix.jpg);}

div#content{color: #ffffff; position: fixed; top: 50%; left: 50%; width: 500px; text-align: center; margin-left: -250px; font-family: verdana; font-size: 30px; z-index: 1000;}
#element1{
     width:99%; 
    height:2000px;
    background:url(img1.png) center 0 fixed;
    position:absolute;
}

#element2{
     width: 99%;
    height:2000px;
    background:url(img2.png) center 0 fixed;
    position:absolute;
}

#element3{
     width:99%;
    height:2000px;
     background:url(img3.png) center 0 fixed;
    position:absolute;
}

/*http://www.alsacreations.com/tuto/lire/1417-zoom-sur-effet-parallaxe.html*/