How to Remove the Black Background Behind the HeaderMenu?

Hello,

Link to the site I am working on so you'll have an idea what I am talking about:

http://myamericanfurnituregalleries.com/

I can't seem to removed the Black Background from the HeaderMenu. I find that there are 2 master.css files and both have the setting for HeaderMenu. One in "App_Themes\administration" directory and the other in "App_Themes\darkOrange" directory.

FIRST TRIED --

I modified the master.css file in "App_Themes\administration" directory FROM:

.header-menu
{
  width: 100%;
  line-height: 29px;
  height:31px;
  background: url('images/admin-menu-bg.gif') repeat-x;  
}

TO:

.header-menu
{
  width: 100%;
  line-height: 29px;
  height:31px;
  background: url('images/MY_NEW_BACKGROUND.gif') repeat-x;  
}

By changing the image file (this is the image with black background). It had no effect at all!



SECOND TRIED --

I modified the master.css file in "App_Themes\darkOrange" directory FROM:

.headermenu
{
  color: #FFFFFF;
  background: #000000;
  padding: 8px 5px 9px 5px;
  text-align: center;
  height: 100%;
  vertical-align: middle;
  letter-spacing: 1px;
  margin-bottom: 10px;
}

.headermenu ul
{
  padding: 0;
  margin: 0;
}

.headermenu li
{
  list-style: none;
  display: inline;
}

.headermenu a
{
  color: #FFF;
  text-decoration: none;
  text-transform: uppercase;
  font-size: 0.9em;
  font-weight: bold;
  vertical-align: middle;
  padding-left: 10px;
  padding-right: 10px;
}


TO:

.headermenu
{
   height: 32px;
   width: 950px;
}

.headermenu ul{margin: 0px auto;}

.headermenu li
{ float: left;
  margin: 0px;
  padding: 0px;
  list-style: none;
}

/* ancors Start
---------------------*/
a{outline: none;}

a, a:link, a:visited {
color:#006699;
text-decoration:none;
}
a:hover {
text-decoration:underline;
}

.headermenu li a
{ display: block;
  float: left;
  height:26px;
  text-decoration: none;
  padding: 6px 19px 0px 19px;
  border-right: 2px solid;
  font-weight: bold;
  background: #935d29;
  color: #4c1d00;
  border-color: #935d29;
  background:transparent url('images/nav_tab_bg.png') no-repeat scroll left top;
}

.headermenu li a:hover, headermenu li a.selected, topmenu li a.selected:hover
{ background: #82974B;
  color: #EEE;
  border-color: #935d29;
    background:transparent url('images/nav_tab_bg.png') no-repeat scroll left top;
  background-position: 0 -34px;
}

Notice that I have removed the "background: #000000; line under .headermenu" and added HOVER to it.

The hoover works but the black background IS NOT REMOVABLE.

Many thanks and Your help is appreciated!