set nav menu to adjust when one tab is removed

[suavedesign]

I am trying to st my nav bar so that if one tab is removed, the rest of the tabs will just enlarge, and continue to take up the full nav bar width. How can I do that?

[almostbob]

<humor>
well If I pull the code you used out of my .behind., it would hurt
could you post your code and save my butt from the sharp edges,
</humor>
<serious>
please post the code for the css menu,
</serious>
and likely somebody will be able to point out the changes

[suavedesign]

HTML

<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>

CSS

#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;
}

[almostbob]

ps,
'somebody' <> me,
able to determine what the guru may need,
css is not my forte
something along the lines of width=100%/(count li) ??