Mozilla renders nested divs OUTSIDE parent div

On this page: http://www.aurafellows.net/aura/research3.asp

in the subnav area (the narrow navbarimmediately below the main top navbar), I have links inside divs that are nested inside the subnav div:  
<div id="subnav">
<div id="subnavFloatleft"> <a href="index.asp" id="home">home</a> </div>
<div id="subnavFloatRight"> <a href="email_updates.asp" id="emailupdate">email updates</a>&nbsp;&nbsp;|&nbsp;&nbsp;<a href="contact.asp" id="contact">contact</a>
</div>
</div>

They look fine in IE and Opera. But in Mozilla FireFox, the links appear outside the subnav div. Anyone knows why?  Thanks in advance.

Here's the CSS:

#subnav {
     width: 95%;       margin: 1%;
      background-color: white;
      padding:5px;
      font-size:75%;
      color:#666666;
      border: solid #ccc 1px;
     }
#subnavFloatleft {
float:left;
      }

#subnavFloatRight {
      float:right;
      
      } /* so the CONTACT and other buttons float right */

      
#subnav a:link, #subnav a:visited, #subnav a:active {
      font-variant:small-caps;
            /*padding: 6px 10px 8px; */
      background: #fff;
      color: #666;
      text-decoration:none;

      }      

#subnav a:hover {
      font-variant:small-caps;
            /*padding: 6px 10px 8px; */
      background: #b5474a;
            color: white;
      text-decoration:none;
      }