img {max-width:100%;height:auto;}

body:after {
      content: "";
      position: fixed;
      top: 0;
      height: 100vh;
      left: 0;
      right: 0;
      z-index: -1;
      background-image: url(../images/orch.jpg);
      background-position: center center;
      -webkit-background-size: cover;
      -moz-background-size: cover;
      -o-background-size: cover;
      background-size: cover;
      background-color: #FFFFFF;
}