<div class="slideshow-container">
<div class="slide">
<img src="images/Aluminum foil tape25.jpg" alt="Image 1" width="960px" height="300px"/>
</div>
<div class="slide">
<img src="images/bushing11.jpg" alt="Image 2" width="960px" height="300px"/>
</div>
<div class="slide">
<img src="images/Graphtie sheet36.jpg" alt="Image 3" width="960px" height="300px"/>
</div>
</div>
<div class="div4">
<div class="div1">
<ul class="ul_style2">
<li><a href="javascript: unfold_Click()">Insulation materials</a>
<ul class="ul_style3" id="u3" style="display:none;">
<li><a>Polyimide tape/film</a></li>
<li><a>Insulation washer</a></li>
<li><a>Natural mica sheet</a></li>
<li><a>Red insulation gasket</a></li>
</ul>

</li>
<li><a href="javascript: unfold0_Click()">Thermal conductive materials</a>
<ul class="ul_style3" id="u4" style="display:none;">
<li><a>Polyimide tape/film</a></li>
<li><a>Insulation washer</a></li>
<li><a>Natural mica sheet</a></li>
<li><a>Red insulation gasket</a></li>
</ul>
</li>
<li><a href="javascript: unfold1_Click()">Hardware materials</a>
<ul class="ul_style3" id="u5" style="display:none;">
<li><a>Polyimide tape/film</a></li>
<li><a>Insulation washer</a></li>
<li><a>Natural mica sheet</a></li>
<li><a>Red insulation gasket</a></li>
</ul>

</li>
</ul>
</div>
<div class="div2"><iframe src="main.html" width="100%" height="100%" scrolling="yes" frameborder="0"></iframe></div>
<div class="div3"></div>
</div>

怎么结果是没有隔开，css里设置了margin-top已经