CSS Help!

I am working on adapating a layout that I found that I like.

I cannot figure out how to get the little white thing on the right to disappear. I am also having trouble because I created pages “about” and “membership” but it goes to 404 not found when I try to click them!

https://www.designbykendall.com/dcc/

Here is the code I have for the nav.css

/*Main Navbar */

#nav {
	font-size:1.1em;
	background: #ffffff;
	text-transform: uppercase;
	width: 810px;
	border-top:#b5dfd3, solid, 15px;
	margin-top: 15px;
	margin-bottom: 15px;
	padding: 0px;
	}

#nav, #nav ul {
	list-style: none;
	line-height: 1;
	}

#nav a, #nav a:hover {
	display: block;
	text-decoration: none;
	border:none;
	float:left;
		}

#nav li {
	float: left;
	list-style:none;
	}

#nav a, #nav a:visited {
	display:block;
	font-weight:bold;
	color: #663300;
	padding-top: 5px;
	padding-right: 20px;
	padding-bottom: 5px;
	padding-left: 20px;
	background-color:#FFFFFF;
	}

#nav a:hover, #nav a:active, .current_page_item	a, #home .on {
	text-decoration:none;
	color: #b5dfd3;
	background: #ffffff;
	}