html, body {
    height: 100%;
    margin: 0;
    padding: 0;
}

img {
    padding: 0;
    display: block;
    margin: 0 auto;
    max-height: 100%;
    max-width: 100%;
}

body {
    background-image: url("pic1.jpg");
    background-color: #cccccc;
   }