代码示例：（标识：demo_rwd_simple）
<!DOCTYPE html>
<html lang="en-US">
<head>
<style>
.city {
float: left;
margin: 5px;
padding: 10px;
width: 300px;
height: 300px;
border: 1px solid black;
}
</style>
</head>
<body>
<h1>Sou-Xun.com Demo</h1>
<h2>Resize this responsive page!</h2>
<br>
<div class="city">
<h2>London</h2>
<p>London is the capital city of England.</p>
<p>It is the most populous city in the United Kingdom,
with a metropolitan area of over 13 million inhabitants.</p>
</div>
<div class="city">
<h2>Paris</h2>
<p>Paris is the capital and most populous city of France.</p>
</div>
<div class="city">
<h2>Tokyo</h2>
<p>Tokyo is the capital of Japan, the center of the Greater Tokyo Area,
and the most populous metropolitan area in the world.</p>
</div>
</body>
</html>
