请问下，3个div（ index_menu，index_content，index_right无法在同一个位置上面，index_content掉下去了，请问下，这个应该怎么弄？哪里弄错了呢？
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index2.html文件
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<link rel="stylesheet" href="css/css.css" type="text/css" />
<title>001</title>
</head>
<body>
<div id="main">
<div id="top"><img src="images/Cafe Niche-world.png" width="509" height="60" alt="咖啡尼积" /></div>
<div id="content">
<div id="index_menu">index_menu</div>
<div id="index_content">index_content</div>
<div id="index_right">index_right</div>
</div>
<div id="bottom"></div>
</div>
</body>
</html>
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css文件
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*{
margin:0px;
padding:0px;
}
body { font-family:Verdana; font-size:14px; margin:0;}
#main{
margin:0 auto;
width:1100px;
background:url(../images/index_bg.jpg);
}
#top {
height:45px;
padding:30px;0px;5px;150px;
}
#content {
width:1100px;
height:700px;
margin-bottom:5px;
}
#bottom {
height:45px;
}
#index_menu{
width:310px;
height:550px;
float:left;
background-color:#969;
}
#index_content{
width:480px;
height:550px;
background-color:#090;
/* background:url(../images/index_content.png); */
}
#index_right{
width:310px;
height:550px;
background-color:#063;
}
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