Navbar en footer niet in het midden.

.navbar {
width:335px;
margin:0 auto;
list-style:none;
position:absolute;
}

.navbar li {
float:left; 
margin:auto;
}

.navbar a {
display:block;
text-align:center;
width:100px; /* fixed width */
text-decoration:none;
color:#FFF;
font-family:Tahoma, Geneva, sans-serif;
font-size:18px;
background-image:url(images/knopa.jpg);
}

#footer {
	font-family:Verdana, Geneva, sans-serif;
	font-size:12px;
	margin-top:700px;
	text-align:center;
	position:fixed;
}

#footer a{
	color:#FFF;
	text-decoration:none;
	margin-left:auto;
	text-align:center;
}

<div id="menu_wrapper">
<div id="menu">
<ul>
<li><a href="#">knop1</a></li>
<li><a href="#">knop2</a></li>
</ul>
</div>
</div>

#menu_wrapper, #menu, #menu ul, #menu li, #menu a {
	margin: 0;
	padding: 0;
	border: 0;
	outline: 0;
	background: transparent;
	line-height: 1;
}
#menu_wrapper {
	width: 335px;
	/* 2 regels hieronder alleen voor test */
	height: 44px;
	background-color: #aaa;
}
#menu {
	width: 100%;
	text-align: center;
}
#menu ul {
	position: relative;
	list-style-type: none;
	float: left;
	left: 50%;
	top: 0;
	text-align: center;
}
#menu li {
	float: left;
	vertical-align: middle;
	width: auto;
	right: 50%;
	display: block;
	position: relative;
}
#menu a {
	display: block;
	text-decoration: none;
	width: 100px; /* zie noot */
	padding: 13px 10px 13px 10px; /* zie noot */
	font-family: tahoma, geneva, sans-serif;
	font-size: 18px;
	color: #fff;
	background-image: url(images/knopa.jpg);
	cursor: pointer;
	/* regel hieronder alleen voor test */
	background-color: #00f;
}
/* 3 regels hieronder alleen voor test */
#menu li:hover a {
	background-color: #f00;
}