#back{
    height: 99%;
    margin: 0px;
    padding: 0px;
       -webkit-background-size: cover !important;
    -moz-background-size: cover !important;
    -o-background-size: cover !important;
    background-size: cover !important;
    background-repeat: repeat-y;
    top: 0;
    left: 0;
   width: 100%!important;
    height: 100%!important;
    background-attachment: fixed;
z-index:-1;
}








@media only screen and (max-width: 768px) {
#back
 {
background: url(../../fileadmin/background-images/ArztPadH.jpg);

}
}


@media only screen and (max-width: 1024px) and (orientation: landscape){
#back
 {
background: url(../../fileadmin/background-images/ArztPadQ.jpg);

}
}


@media only screen and (min-width: 1025px) and (max-width: 1689px) {
#back
 {
background: url(../../fileadmin/background-images/ArztS.jpg);

}
}

@media only screen and (min-width: 1690px) and (max-width: 1919px) {
#back
 {
background: url(../../fileadmin/background-images/ArztM.jpg);

}
}




@media only screen and (min-width: 1920px ) and (max-width: 2559px) {
#back
 {
background: url(../../fileadmin/background-images/ArztL.jpg);

}
}


@media only screen and (min-width: 2560px) {
#back
 {
background: url(../../fileadmin/background-images/ArztXL.jpg);

}
}