在线运行代码 - 代码学院 www.codexy.cn

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta charset="utf-8"> 
<title>代码学院(codexy.cn)</title> 
<style>
div {
    width: 100%;
    height: 400px;
    background-image: url('/wp-content/uploads/2015/06/img_flowers.jpg');
    background-size: 100% 100%;
    border: 1px solid red;
}
</style>
</head>
<body>

<p>调整浏览器大小查看效果。</p>

<div></div>

</body>
</html>

源代码

动行结果