In ATO>Add HTML/CSS Inserts>CSS Inserts you will see something like the following.
HTML Code:
/* Menu Bars */
div#menu1 ul.rMenu-ver {
-moz-border-radius:5px;
-khtml-border-radius: 50px;
-webkit-border-radius:5px;
border-radius: 5px;
padding: 5px;
/* the background color of sub-UL's must be set here */
background: #ccc;
box-shadow: 0 3px 10px #6663;
-moz-box-shadow: 0 10px 5px #666;
}
To get rid of the background change the background to transparent and eliminate the shadow as in the following.
HTML Code:
/* Menu Bars */
div#menu1 ul.rMenu-ver {
-moz-border-radius:5px;
-khtml-border-radius: 50px;
-webkit-border-radius:5px;
border-radius: 5px;
padding: 5px;
/* the background color of sub-UL's must be set here */
background: transparent;
}
This is the kind of stuff where having a better knowledge of CSS is helpful as there isn't just a button to click. Many of the style setting are in ATO>Add HTML/CSS Inserts>CSS Inserts or are CSS in other settings boxes in the theme options.