html { 
  margin:0;
  padding:0;
  background: url(wallpapper.jpg) no-repeat center fixed; 
  -webkit-background-size: cover;
  -moz-background-size: cover;
  -o-background-size: cover;
  background-size: cover;
}

div#colonne1 {
    float: left;
    width: 440px;
    margin-right: 0px;
    background:;
    text-align:center;
}
div#colonne2 {
    float: right;
    width: 410px;
    margin-left: 0px;
    background:;
    text-align:center;
}
div#centre {
    overflow:visible;
    background:;
}