#i1740 {
  background-image:url(../image/top/bg01.jpg);
  background-repeat:no-repeat;background-size:cover;background-position:center center;
}
@media screen and (min-width:641px) and (max-width:835px) {
  #i1740 {
    background-image:url(../image/top/bg01.jpg);
  }
}