Impostare lo sfondo adattivo:
<style type="text/css">
html, body {
width: 100%;
height: 100%;
margin-top: 0px;
padding-top: 0px;
top: 0px;
margin-left: 0px;
padding-left: 0px;
left: 0px;
}
body {
overflow: hidden;
}
#background {
width: 100%;
height: 100%;
}
</style>
</head>
<body>
<img id="background" alt="background" src="flower-wallpaper.jpg">