I think I understand what you're asking, but maybe not. Check this out. I went overboard on the CSS, but it just illustrates the point. Here's a Fiddle.
<div class="navItems">
<div class="navOutline">
<ul>
<li><a href="#">Item 1</a></li>
<li><a href="#">Item 2</a></li>
<li><a href="#">Item 3</a></li>
<li><a href="#">Item 4</a></li>
<!-- Add more items and it'll expand -->
<li><a href="#">Item 5</a></li>
</ul>
</div>
</div>
.navItems ul { list-style:none; margin:0; padding:0; }
.navItems li { display:inline; }
.navItems li:not(:last-child) { margin-right:10px }
.navItems .bumper { margin-right:15px; }
.navItems {
float:left;
font-size:14px;
padding:5px;
background:#FFF;
box-shadow:0px 0px 20px rgba(0,0,0,0.25);
-o-box-shadow:0px 0px 20px rgba(0,0,0,0.25);
-ms-box-shadow:0px 0px 20px rgba(0,0,0,0.25);
-moz-box-shadow:0px 0px 20px rgba(0,0,0,0.25);
-webkit-box-shadow:0px 0px 20px rgba(0,0,0,0.25);
}
.navOutline {
margin:auto auto;
padding:10px;
background:#FFF;
border:1px dashed #CCC;
}
.navItems a { text-decoration:none; color:#000; }