<style type="text/css">
div{
width: 800px;
height: 500px;
border: 1px solid #000;
background: url(img/am.jpg) no-repeat;
/* background-size:100px 200px; */
/* background-size:500px; */
/* background-size:100%; */
/* background-size:cover; */
background-size: contain;
}
</style>
</head>
<body>
<div></div>
</body>
