.header{
    position: absolute;
    width: 100%;
    top: 0;
    left: 0;
    z-index: 999;
}
.banner img{
    width: 100%;
    min-height: 50vh;
    display: block;
    object-fit: cover;
}
@media only screen and (max-width:768px) {
  .banner img{
    width: 100%;
    min-height: 0px;
    height: 100px;
    display: block;
    object-fit: cover;
}
}