<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<style>
body {
background-color: lightgreen;
}
@media only screen and (max-width: 600px) {
body {
background-color: lightblue;
}
}
</style>
</head>
<body>
<p>请调整浏览器窗口的大小。如果此文档的宽度为 600 像素或更小,背景颜色为“浅蓝色”,否则为“浅绿色”。</p>
</body>
</html>