代码示例：（标识：css3_background-size）
<!DOCTYPE html>
<html>
<head>
<style>
#example1 {
border: 1px solid black;
background: url(/static/demo/images/flower.gif);
background-size: 100px 80px;
background-repeat: no-repeat;
padding: 15px;
}
#example2 {
border: 1px solid black;
background: url(/static/demo/images/flower.gif);
background-repeat: no-repeat;
padding: 15px;
}
</style>
</head>
<body>
<h1>background-size 属性</h1>
<p>被调整大小的 background-image:</p>
<div id="example1">
<h2>Welcome to Shanghai</h2>
<p>Shanghai is one of the four direct-administered municipalities of the People's Republic of China. Welcome to Shanghai!</p>
<p>The city is located on the southern estuary of the Yangtze, with the Huangpu River flowing through it.</p>
</div>
<p>background-image 的原始尺寸：</p>
<div id="example2">
<h2>Welcome to Shanghai</h2>
<p>Shanghai is one of the four direct-administered municipalities of the People's Republic of China. Welcome to Shanghai!</p>
<p>The city is located on the southern estuary of the Yangtze, with the Huangpu River flowing through it.</p>
</div>
</body>
</html>
