set nav menu to adjust when one tab is removed

<div id="topnav">
<ul>
<li><a href="<?php echo $siteurl; ?>myprofile" <?php if ($section == 'myprofile') { echo 'class="lion"' ; } ?>>My Profile</a></li>
<li><a href="<?php echo $siteurl; ?>teams" <?php if ($section == 'teams') { echo 'class="lion"' ; } ?>>Family Teams</a></li>
<li><a href="<?php echo $siteurl; ?>mt-tellafriend" <?php if ($section == 'fundraising') { echo 'class="lion"' ; } ?>>Fundraising</a></li>
<li><a href="<?php echo $siteurl; ?>mt-training" <?php if ($section == 'training') { echo 'class="lion"' ; } ?>>Training</a></li>
<li><a href="<?php echo $siteurl; ?>mt-recommit" <?php if ($section == 'recommitment') { echo 'class="lion"' ; } ?>>Recommitment</a></li>
<li><a href="<?php echo $siteurl; ?>forum" <?php if ($section == 'forum') { echo 'class="lion"' ; } ?>>Forum</a></li>
<li class="last"><a href="<?php echo $siteurl; ?>info" class="feedback">Send Us Feedback</a></li>
<div class="clear"></div>
</ul>
</div>

#pages.profile.letters #topnav{
	margin:-195px 0  0 -49px;
	width:1040px;
}
 
#pages.profile.letters #topnav li{
	display:inline;
	float:left;
	list-style-type:none;
	background:#2765ae;
	/*padding:50px 0px 50px 0px;*/
	padding:50px 25px;
	margin:0 1px 0 0;
	text-transform:uppercase;
	font-family: 'gothambook';
	/*width:100%;*/
	text-align:center;
}
 
#pages.profile.letters #topnav li.last{
	margin:0px;
	background:#000000;
	font-size:28px;
	font-family: 'bebasneue';
	padding:41px 16px 41px 16px;
	/*width:20.8%;*/
}
 
#pages.profile.letters #topnav li:hover{
	background:#ffc90d;
}
 
#pages.profile.letters #topnav li:hover a{
	color:#2765ae;
}
 
#pages.profile.letters #topnav li a{
	color:#FFFFFF;
	text-decoration:none;
}

<ul id="topnav">
  <li><a href="">blah blah</a></li>
  ...
</ul>
==============
#topnav {
  display: table;
  width: 100%;
  }
 
#topnav li {
  display: table-cell;
  }