Menu Layout works in all browsers EXCEPT iPhone - iphone

Question

I have a menu very similar to the menu here on StackOverflow. The problem is that my menu looks right in every browser I've tested it on EXCEPT for my iPhone.
Here is a screenshot of the iPhone
Now obviously the "Add Event" button is supposed to be the same size as the rest.
Here's my Markup
<div id="menucontainer">
<div class="floatleft">
<ul class="menu">
<li><%: Html.NavigationLink("Now", "Index", "Events")%></li>
<li><%: Html.NavigationLink("Coming", "Coming", "Events")%></li>
<li><%: Html.NavigationLink("Hot", "Hot", "Events")%></li>
<li><%: Html.NavigationLink("Tags", "Index", "Tags")%></li>
<li><%: Html.NavigationLink("Users", "Index", "Users")%></li>
</ul>
</div>
<div class="floatright">
<ul class="menu">
<li><%: Html.NavigationLink("Add Event", "AddEvent", "Events")%></li>
</ul>
</div>
</div>
And here's my CSS
#menucontainer{position:relative; width:675px; float:right;}
ul.menu
{
padding: 0 0 2px;
position: relative;
margin: 0;
}
ul.menu li
{
display: inline;
list-style: none;
}
ul.menu li a
{
padding: 8px 18px;
font-weight: bold;
text-decoration: none;
line-height: 2.8em;
background-color: #666;
color: #fff;
border: 1px solid black;
text-shadow:#000 0px 1px 1px;
}
ul.menu li a.youarehere
{
background-color:#brand_color;
color: #fff;
}
ul.menu li a:hover
{
background-color:#brand_color;
text-decoration: none;
}
ul.menu li a:active
{
background-color:#brand_color;
text-decoration: none;
}
ul.menu li.selected a
{
background-color:#brand_color;
color: #000;
}
.floatright
{
float: right;
}
.floatleft
{
float: left;
}
Unfortunately I can't figure this one out. Thanks in advance for any direction.
EDIT:
This is the final output being sent to the browser
<div id="menucontainer">
<div class="floatleft">
<ul class="menu">
<li><a class="youarehere" href="/">Now</a></li>
<li>Coming</li>
<li>Hot</li>
<li>Tags</li>
<li>Users</li>
</ul>
</div>
<div class="floatright">
<ul class="menu">
<li>Add Event</li>
</ul>
</div>
</div>
EDIT:
Reproduction on jsbin
http://jsbin.com/akadi3/2 (note: obviously you need the iOS browser to see the problem)

Answer 1

Ok, so after a LOT of fiddling around, it appears as though if I add a height attribute to the menucontainer, then I'm all good.
#menucontainer
{
position:relative;
width:675px;
height:40px; /* this fixed the problem */
float:right;
font-size:80%;
}