body, html {
    margin:0;
    height: 100vh;
    width: auto;
}
  
  .bg {
    /* The image used */
    background-image: url("banner.jpg");
    /* Full height */
    height: 100vh;
  
    /* Center and scale the image nicely */
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
  }