I have a menubar made of li elements, each floating left to have them side-by-side.
This works on on most brwsers but not on my customer's firefox (mac version 26)
the li are a bit larger making them overflow at the end of the line (10px together probably)

Any idea why? I have a css reset and margin and padding are set to a value.

this is html:

```
<ul id="menu">
                <li class="menuItem"><a class="menuItemLink" href="interface.php?type=architecture&amp;page=projets-realisations">projets-realisations</a>
                    <ul class="subMenu">
                        <li class="subMenuItem"><a class="subMenuItemLink" href="interface.php?type=architecture&amp;page=projets-realisations-en-resume">En résumé</a></li>
                        <li class="subMenuItem"><a class="subMenuItemLink" href="interface.php?type=architecture&amp;page=projets-realisations-az">De A à Z</a></li>
                    </ul>
                </li>
                <li class="menuItem"><a class="menuItemLink" href="interface.php?type=architecture&amp;page=portes-parquets-escaliers">Portes-parquets-escaliers</a> </li>
                <li class="menuItem"><a class="menuItemLink" href="interface.php?type=architecture&amp;page=cuisines-salles-de-bain">cuisines-salles de bain</a> </li>
                <li class="menuItem"><a class="menuItemLink" href="interface.php?type=architecture&amp;page=decoration-tentures">decoration-tentures</a> </li>
                <li class="menuItem"><a class="menuItemLink" href="interface.php?type=architecture&amp;page=de-ville-en-ville">de ville en ville</a> </li>
                <li class="menuItem"><a class="menuItemLink" href="interface.php?type=architecture&amp;page=espace-animalier">espace animalier</a> </li>
            </ul>

```

css:

```
.menuItem {float:left; cursor: default; position: relative; margin-left:4px; padding:0px; margin-right:0px;}
.menuItem:last-child {margin-right:-50px;}
.menuItemLink {line-height: 20px; color: #ffffff; text-transform: uppercase; font-size: 13px; padding-left:5px; padding-right: 5px; text-decoration: none;}

```

The margin-right -50 is just to mae sure the last elements doesn't goes on a new line...
Why is it miscalculated by his firefox? The strangest thing is I tried the same firefox version on a mac (different osversion) and don't have this issue.