border left/right error in firefox

hi everyone,

i have been trying to align border left/right correctly in ff but it always crates gap on top and bottom (see screenshot)

http://img150.imageshack.us/img150/4125/fferrorso2.th.gif (http://img150.imageshack.us/my.php?image=fferrorso2.gif)

while on ie it works as supposed to (screenshot below)

http://img143.imageshack.us/img143/1484/iecorrectzt9.th.gif (http://img143.imageshack.us/my.php?image=iecorrectzt9.gif)


here is my code

#center_container{margin-left:118px;margin-top:24px;}
#center_container_text{
width: 522px;
border-left:1px solid #757d7b;
border-right:1px solid #757d7b;
}
#banners{float:right;margin-top:20px;margin-bottom: 10px;width:100px;border: 1px solid black;}


<div id="center_container">
<div id="banners">
<p>a</p>
<p>&nbsp;</p>
<p>&nbsp;</p>
<p>&nbsp;</p>
<p>asd</p>
<p>asd</p>
<p>as</p>
<p>d</p>
</div>
<div><img src="images/box_header.gif" name="Categories_header" alt="" /></div>
<div id="center_container_text">
<p>a</p>
<p>&nbsp;</p>
<p>asd</p>
<p>asd</p>
<p>as</p>
<p>d</p>
<p>asd</p>
</div>
<div><img src="images/box_bottom.gif" name="Categories_bottom" alt="" /></div>
</div>

thx.

img {display:block;}
http://developer.mozilla.org/en/docs/Images,_Tables,_and_Mysterious_Gaps