Semi-transparent background on drop down menu

Hi,

I have created a drop down menu in Dreamweaver, which drops down over an image. At the moment, the background of the drop down menu is solid white. Can someone please tell me how I can make it semi-transparent so that the picture it drops down over actually still shows through slightly? It would be really nice if it could fade to the semi-transparent state from the solid white.

Thanks in advance.

Code generated by Dreamweaver is below:

<script language="JavaScript">
<!--
function mmLoadMenus() {
  if (window.mm_menu_0724130109_0) return;
  window.mm_menu_0724130109_0 = new Menu("root",100,20,"Verdana, Arial, Helvetica, sans-serif",10,"#666666","#666666","#ffffff","#fbdfca","left","middle",5,0,1000,-5,7,true,false,true,0,false,true);
  mm_menu_0724130109_0.addMenuItem("Bob");
  mm_menu_0724130109_0.addMenuItem("Harry");
  mm_menu_0724130109_0.addMenuItem("Russell");
  mm_menu_0724130109_0.addMenuItem("Keira");
  mm_menu_0724130109_0.addMenuItem("Mike");
  mm_menu_0724130109_0.addMenuItem("David");
  mm_menu_0724130109_0.addMenuItem("Jackie");
  mm_menu_0724130109_0.addMenuItem("Michelle");
  mm_menu_0724130109_0.addMenuItem("Laura");
   mm_menu_0724130109_0.fontWeight="bold";
   mm_menu_0724130109_0.hideOnMouseOut=true;
   mm_menu_0724130109_0.menuBorder=0;
   mm_menu_0724130109_0.menuLiteBgColor='#ffffff';
   mm_menu_0724130109_0.menuBorderBgColor='#ffffff';
   mm_menu_0724130109_0.bgColor='#ffffff';

  mm_menu_0724130109_0.writeMenus();
} // mmLoadMenus()

//-->
</script>

...

<td><a href="#" onMouseOut="MM_startTimeout();" onMouseOver="MM_showMenu(window.mm_menu_0724130109_0,0,19,null,'button');"><img name="button" src="button.gif" width="89" height="16" border="0" alt=""></a></td>