可在CSS中利用width属性和height属性控制一个图像得到大小，就像控制其他任何盒子的大小一样。
<html>
<head>
<title>TODO supply a title</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<style type="text/css">
img.large {
500px;
height:500px;}
img.medium {
250px;
height: 250px;}
img.small{
100px;
height:100px; }
</style>
</head>
<body>
<div>TODO write content</div>
<img src="magnolia-large.jpg" alt="Magnolia"/>
<img src="magnolia-medium.jpg" alt="Magnolia"/>
<img src="magnolia-small.jpg" alt="Magnolia"/>
</body>
</html>