[gb2world]

You can use Firefox+Firebug to look directly at the css settings. You can make changes on the fly and debug to see what works, then make the changes directly to the appropriate css files:

/cart/skin/common_files/modules/One_Page_Checkout/main.css

fieldset.registerform ul {
background: transparent;
margin: 0;
padding: 0 15px;
position: relative;
}


div.opc-section-container {
background: transparent;
margin: 0;
padding: 10px 0;
}