请问错哪了？为什么没有定位导航的效果？
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<title>地狗购物网站</title>
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<body>
<div id="menu">
<ul>
<li><a href="#item1" class="current">1F 男装</a></li>
<li><a href="#item2">2F 女装</a></li>
<li><a href="#item3">3F 美妆</a></li>
<li><a href="#item4">4F 数码</a></li>
<li><a href="#item5">5F 母婴</a></li>
</ul>
</div>
<div id="content">
<h1>地狗购物网</h1>
<div id="item1" class="item">
<h2>1F 男装</h2>
<ul>
<li><a href="#"><img src="../../../images/star/8.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/8.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/8.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/8.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/8.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/8.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/8.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/8.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/8.jpg" alt="" /></a></li>
</ul>
</div>
<div id="item2" class="item">
<h2>2F 女装</h2>
<ul>
<li><a href="#"><img src="../../../images/star/6.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/6.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/6.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/6.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/6.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/6.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/6.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/6.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/6.jpg" alt="" /></a></li>
</ul>
</div>
<div id="item3" class="item">
<h2>3F 美妆</h2>
<ul>
<li><a href="#"><img src="../../../images/star/7.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/7.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/7.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/7.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/7.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/7.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/7.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/7.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/7.jpg" alt="" /></a></li>
</ul>
</div>
<div id="item4" class="item">
<h2>4F 数码</h2>
<ul>
<li><a href="#"><img src="../../../images/star/11.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/11.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/11.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/11.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/11.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/11.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/11.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/11.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/11.jpg" alt="" /></a></li>
</ul>
</div>
<div id="item5" class="item">
<h2>5F 母婴</h2>
<ul>
<li><a href="#"><img src="../../../images/star/16.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/16.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/16.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/16.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/16.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/16.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/16.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/16.jpg" alt="" /></a></li>
<li><a href="#"><img src="../../../images/star/16.jpg" alt="" /></a></li>
</ul>
</div>
</div>
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