if (screen.width >= 1600) {
  document.write('<style type="text/css"><!-- body { background-attachment: fixed; background-image: url(../images/1600.jpg); background-repeat: no-repeat; background-position: center top;} --></style>');
} else {
  if (screen.width >= 1520) {
    document.write('<style type="text/css"><!-- body { background-attachment: fixed; background-image: url(../images/1520.jpg); background-repeat: no-repeat; background-position: center top;} --></style>');
  } else {
    if (screen.width >= 1440) {
      document.write('<style type="text/css"><!-- body { background-attachment: fixed; background-image: url(../images/1440.jpg); background-repeat: no-repeat; background-position: center top;} --></style>');
    } else {
      if (screen.width >= 1360) {
        document.write('<style type="text/css"><!-- body { background-attachment: fixed; background-image: url(../images/1360.jpg); background-repeat: no-repeat; background-position: center top;} --></style>');
      } else {
        if (screen.width >= 1280) {
        document.write('<style type="text/css"><!-- body { background-attachment: fixed; background-image: url(../images/1280.jpg); background-repeat: no-repeat; background-position: center top;} --></style>');
        } else {
          if (screen.width >= 1152) {
            document.write('<style type="text/css"><!-- body { background-attachment: fixed; background-image: url(../images/1152.jpg); background-repeat: no-repeat; background-position: center top;} --></style>');
          } else {
            if (screen.width >= 1024) {
              document.write('<style type="text/css"><!-- body { background-attachment: fixed; background-image: url(../images/1024.jpg); background-repeat: no-repeat; background-position: center top;} --></style>');
            } else {
              document.write('<style type="text/css"><!-- body { background-attachment: fixed; background-image: url(../images/800.jpg); background-repeat: no-repeat; background-position: center top;} --></style>');
            }
          }
        }
      }
    }
  }
}
