i made this lil nav menu and it works fine in firebird 0.7 and ie6 but in opera for some reason there is a small gap between the last menu item and the right hand side of the menu.
i tried increasing the li size but that only makes the list wrap.
increasing the a element's size would only cause the links to overlap.
i'm pretty sure that it's probably something simple lilke forgetting to dot an i or cross a t (i read these forums a lot and it often is) but i just cant see what.

here's the code

Code:
 <style type="text/css">
<!--
.nav{
position:relative;
color:#000;
height:1em;
font:1em arial, sans-serif;
width:50%;
}
.nav h3{
margin:0;
background: #a9a9a9;
}
.nav ul{
background: #4169e1;
list-style:none;
margin:0;
padding-left:0;
float:left;
width:100%;
text-align:center;
}
.nav ul li{
float:left;
margin:0;
width:33.3%;
}
.nav ul li a{
display:block;
color:white;
text-decoration:none;
padding: 0;
width:100%;
}
.nav ul li a:hover{
background: #99ccff;
}
.listbox{
position:relative;
top:0;
border:6px dashed #000;
border-left-style: solid;
border-right-style: solid;
}
#next{
background: #ffe4c4;
clear:both;
margin-top:0;
color:#000;
}
-->
                    </style>
    <title>
      list practise
    </title>
  </head>
  <body>
    <div class="nav">
      <div class="listbox">
        <h3>
          navigation
        </h3>
        <ul>
          <li>
            <a href="#">link one</a>
          </li>
          <li>
            <a href="#">second link text</a>
          </li>
          <li>
            <a href="#">3rd</a>
          </li>
        </ul>
        <div id="next">
        </div>
      </div>
    </div>
  </body>