change menu tabs with css

Whew! what a process. I got a lot of it worked out.

#nav {
  	background-image: url(images/abc.png);
	background-repeat: repeat-y;
	padding-bottom: 2px;
	margin-bottom: 2px;
}
#nav ul {
	display: block;
	float: left;
	vertical-align: bottom;
    list-style: none outside none;
    margin: 0 0 -1px 170px;
    padding: 0;
}
#nav ul li {
    border: none;
    float: left;
    margin: 0 55px 0 0;
    padding: 0;
	border-radius: 0px;
}
#nav ul li a {
    display: inline-block;
    padding: 6px 8px 5px;
    text-decoration: none;
	background-color: transparent;
	border-radius: 0px;
}
#nav ul li a:hover {
	background-color: #ff7b00;
	background-image: none;
	border-radius: 0px;
}
#nav .current_page_item a, #nav .current_page_item a:hover, #nav li a:active {
    text-decoration: none;
	background-color: #ff7b00;
	background-image: none;
	border-radius: 0px;
}
#nav .current_page_item a, #nav .current_page_item a:hover, #nav li a:active {
    color: red;
	border-radius: 0px;
}
#nav .current_page_item {
    background-color: white;
	border-radius: 0px;
}
#nav .current {
    background-color: white;
}
#nav a.current, #nav a.current:visited, #nav a.current:hover, #nav a.current:active, #nav li a:hover {
	color: #444;
	border-radius: 0px;
}
#nav li {
    float: left;
    position: relative;
    z-index: 1;
}
#nav li a:hover, #nav li:hover {
    z-index: 100;
}
#nav ul li, #nav ul li a {
    border-top-left-radius: 0px;
    border-top-right-radius: 0px;
}
#nav a, #nav a:visited {
    display: block;
    font-size: 100%;
    font-weight: bold;
    height: 22px;
    line-height: 22px;
    text-decoration: none;
	color: #fff;
}
#nav a {
    border-top: 1px solid #fff;
	border-bottom: 1px solid #fff;
    border-top-left-radius: 0px;
    border-top-right-radius: 0px;
}

Some parts are still unclear to me.
I’ve tried to get rid of the tab right and left hand curved radii; no success. I’ve liberally tried using “border-radius: 0px;”. I tried change them in the rounded-corners.css file. All of this done in a child theme.
Any thoughts out there?

Hi Andrew,
I used the WP/Suffusion functionality menu creation. Appearance –> Menus –> create a menu. Placed below the header. It’s not on the demo site. It’s not live yet. Hopefully that’s enough information.
thanks for getting back to me.
Cheers,
Marioo