我怎样才能让这个div在IE8中扩展并溢出它的容器？

I found a nice css3 dropdown script, but I can't abandon ie8 users because last I read the are still 10% of visits. So, I tried this:

<div id="containerdiv" style="height: 35px; overflow: visible;" > 
<a href="#"><img src="images/1.jpg"></a>
<a href="#"><img src="images/2.jpg"
onmouseenter="document.getElementById('navdd1').style.display = ''"></a>
<div id="navdd1" 
   style="
          display: none; 
          margin-left: 100px; 
          background-image:url('images/blank_dropdown.jpg');
          line-height: 35px;
          width: 100px;"
   onmouseleave="document.getElementById('navdd1').style.display = 'none'">
  <a href="#">Link 1</a><br>
  <a href="#">Link 2</a><br>
</div>
</div>

The mouseenter and mouseleave seem to do what I want, but the un-hidden div stretches the container instead of overflowing it. I'll use php to detect their browser and only present this when they are on IE < 9. Ironically, the overflow portion of this does what I want in FF, but of course the mouseleave does not. How do I make this work?

You should set #navdd1 in position:absolute;.

#navdd1 {
          display: none; 
          margin-left: 100px; 
          background-image:url('images/blank_dropdown.jpg');
          line-height: 35px;
          width: 100px;
          position:absolute;
}

and probably #containerdiv in position:relative; to easily give coordonates to #navdd1.