Styling navigation

Bellow is the CSS for navigation in my. I have an image of an envelope that I would like to use as button to a contact page, the problem is that not all of the envelope is showing up in my navigation. You can see the problems I’m having at https://www.coolmac.org/. The button I am struggling with is in the right-hand corner of the header image.

Thanks in advance.

#nav {
	list-style: none;
	margin: 0px;
	position: absolute;
	right: 10px;
	bottom: 10px;
}
#nav li {
	float: left;
	margin-left: 5px;
}
#nav .current_page_item a, #nav .current_page_item a:visited{
	color: #000000;
	text-decoration: none;
}
#nav .page_item a{
	color: #ffffff;
	text-decoration: none;
	background: #5c8d0c url(images/contact.png) no-repeat;
	padding: 5px 15px;
	font: bold 14px/100% Arial, Helvetica, sans-serif;
	border-top: 1px solid #E6EED0;
	border-left: 1px solid #AFCD69;
	border-right: 1px solid #AFCD69;
	display: block;
}
#nav .page_item a:hover {
	color: #000000;
}