帮忙看一下，为什么没有反应？
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>jQuery动画特效</title>
<style>
div{ background-color:red;
width:60px;
height:60px;
position:relative;
vertical-align:center;
position:absolute;
left:50px;
top:60px;
word-break:;
}
</style>
</head>
<body>
<script type="text/javascript">
$(function(){
$("#left").click(function(){ $("div").animate({left:'-=50px'},1000);});
$("#right").click(function(){ $("div").animate({left:'+=50px'},1000);})
});
</script>
<input type="button" value="左移" id="left"/>
<input type="button" value="右移" id="right"/>
<div align="center">大家好!</div>
</body>
</html>
