div#backgrondindex{
    
    display: table-cell;
    text-align: center;
    vertical-align: middle;
    text-shadow: 1px 1px 10px black;
    user-select: none;
}



header{
    background: url("https://www.octetnova.fr/img/fontnashville.png");
    height: 105% ;
    width: 100%;
    background-attachment: fixed;
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
   
}

header,div.backgrondindex{
    text-align: center ;
    color: white;
    user-select: none;
}