#footer, #footer ul {
  padding: 0;
  margin: 0;
  list-style: none;
  line-height: 22px;
  float: center;
  width: 760px;
  color: #000000;
  border-top: 1px solid #FF0000;
}

#footer li{
  float: left;
  /*width: 10em;  largeur obligatoire, sinon opera devient fou */
  /*width: 100px;*/
  background-color: transparent;
  text-align: center;
  padding: 2px;
  border: 1px solid #000000;
}

#footer a:link, #footer a:visited, #footer a:active {
  display: block;
  /*width: 10em;*/
  /*width: 100px;*/
  text-decoration: none;
  font-size: 12px;
  color: #000000;
  margin-left: 2px;
  margin-right: 2px;
}

#footer a:hover {
  text-decoration: underline;
}

<ul id="footer">
  <li>foo1</li>
  <li>foo2</li>
</ul>