Quick Re-Orders .css problem

[tpeck]

I have a problem trying to rid an image of a black border in the Quick Re-Orders box:



I changed the image to suit the site, and can't work out why the black border.

Any ideas which .css file is involved? I've tried all of them in the template I am using. Here is the code that is being used:

<div id="navColumnTwoWrapper" style="width: 165px"><!--// bof: orderhistory //-->
<div style="width: 165px" id="orderhistory" class="box">			
	<div class="box_border">	
		<div class="box_head">
			Quick Re-Order		</div>
		<div class="box_body">
			<div id="orderhistoryContent" class="sideBoxContent">
<ul class="orderHistList">
<li><a href="http://aapress.com.au/zencart/index.php?main_page=product_info&amp;products_id=57">Essay Correction</a>&nbsp;&nbsp;<a href="http://aapress.com.au/zencart/index.php?main_page=index&amp;action=cust_order&amp;pid=57"><img src="includes/templates/template_default/images/icons/cart.gif" alt="Add this product to your cart by clicking here." title=" Add this product to your cart by clicking here. " width="108" height="29" /></a></li>
<li><a href="http://aapress.com.au/zencart/index.php?main_page=product_info&amp;products_id=105">WORKBOOK for the 404 Study Guide CD-ROM -General Training Module</a>&nbsp;&nbsp;<a href="http://aapress.com.au/zencart/index.php?main_page=index&amp;action=cust_order&amp;pid=105"><img src="includes/templates/template_default/images/icons/cart.gif" alt="Add this product to your cart by clicking here." title=" Add this product to your cart by clicking here. " width="108" height="29" /></a></li>
</ul>
</div>		
		</div> 		
		<div class="clear"></div>
	</div>
</div>
<!--// eof: orderhistory //-->