急求各位大侠指教，小弟初学遇到困难

这段代码我想让图片鼠标移上去能把图片缩小，并且连接依然存在，鼠标移开恢复，试了各种方法都不起效果呀，求大侠指教
换图片链接也有过，style，都不行，求指教~
<!DOCTYPE html>
<html>
<head>
<title>Welcome To Long's World</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<link href="homepagecss.css" rel="stylesheet" />
<link rel="stylesheet" href="960.css"/>
<link rel="stylesheet" href="reset.css"/>
</head>
<body>
<div class="grid_3" id="logo">
<h1>welcome to my world</h1>
<img src="hobby.png" class="foto"/>
</div>
<div class="grid_9" id="nav">
<a href="#"><img src="city2.png" width="203" height="200" id="city"></a>
<a href="#"><img src="school2.png" id="school"></a><br>
<a href="#"><img src="family2.png" width="175" height="164" id="family"></a><br>
<a href="#"><img src="hobby2.png" id="hobby"></a>
<a href="#"><img src="resume2.png" width="174" height="167" id="resume"></a>
</div>
</body>
</html>