@viewport {
   width: device-width;
   zoom: 1;
}

body {
    padding: 0;
    margin: 0;
}

body > div.body-background {
    width: 100vw;
    height: 100vh;
    padding: 0;
    margin: 0;
    background: url(picture.jpg) no-repeat center center;
    background-size: cover;
}