HTML/CSS menu bar dis miss it's shape when resizing window - html

Question

I made a menubar like picture below , Contact item is in the left of Company item , when I resize the browser Contact goes down , what is the problem?
here is picture http://oi61.tinypic.com/64h01g.jpg
HTML
<div id="header"><h1><center>Online Shopping</center></h1></div>
<div id='cssmenu'>
<ul>
<li class='active'><a href='index.html'><span>Home</span></a></li>
<li class='has-sub'><a href='#'><span>Products</span></a>
<ul>
<li><a href='#'><span>Widgets</span></a></li>
<li><a href='#'><span>Menus</span></a></li>
<li class='last'><a href='#'><span>Products</span></a></li>
</ul>
</li>
<li class='has-sub'><a href='#'><span>Company</span></a>
<ul>
<li><a href='#'><span>About</span></a></li>
<li class='last'><a href='#'><span>Location</span></a></li>
</ul>
</li>
<li class='last'><a href='#'><span>Contact</span></a></li>
</ul>
</div>
css
body{
background:#EBEBEB;
}
#header{
padding:0;
margin:0;
height:100px;
background:#6355BD;
}
#cssmenu ul {
margin: 0;
padding: 7px 6px 0;
background: #7d7d7d url(images/overlay.png) repeat-x 0 -110px;
line-height: 100%;
border-radius: 1em;
font: normal 0.5333333333333333em Arial, Helvetica, sans-serif;
-webkit-border-radius: 5px;
-moz-border-radius: 5px;
border-radius: 5px;
-webkit-box-shadow: 0 1px 3px rgba(0, 0, 0, 0.4);
-moz-box-shadow: 0 1px 3px rgba(0, 0, 0, 0.4);
width: auto;
}
#cssmenu li {
margin: 0 5px;
padding: 0 0 8px;
float: left;
position: relative;
list-style: none;
}
#cssmenu a,
#cssmenu a:link {
font-weight: bold;
font-size: 13px;
color: #e7e5e5;
text-decoration: none;
display: block;
padding: 8px 20px;
margin: 0;
border-radius: 5px;
-webkit-border-radius: 5px;
-moz-border-radius: 5px;
text-shadow: 0 1px 1px rgba(0, 0, 0, 0.3);
}
#cssmenu a:hover {
background: #000;
color: #fff;
}
#cssmenu .active a,
#cssmenu li:hover > a {
background: #979797 url(images/overlay.png) repeat-x 0 -40px;
background: #666666 url(images/overlay.png) repeat-x 0 -40px;
color: #444;
border-top: solid 1px #f8f8f8;
-webkit-box-shadow: 0 1px 1px rgba(0, 0, 0, 0.2);
-moz-box-shadow: 0 1px 1px rgba(0, 0, 0, 0.2);
box-shadow: 0 1px 1px rgba(0, 0, 0, 0.2);
text-shadow: 0 1px 0 #ffffff;
}
#cssmenu ul ul li:hover a,
#cssmenu li:hover li a {
background: none;
border: none;
color: #666;
-webkit-box-shadow: none;
-moz-box-shadow: none;
}
#cssmenu ul ul a:hover {
background: #7d7d7d url(images/overlay.png) repeat-x 0 -100px !important;
color: #fff !important;
-webkit-border-radius: 5px;
-moz-border-radius: 5px;
border-radius: 5px;
text-shadow: 0 1px 1px rgba(0, 0, 0, 0.1);
}
#cssmenu li:hover > ul {
display: block;
}
#cssmenu ul ul {
z-index: 1000;
display: none;
margin: 0;
padding: 0;
width: 185px;
position: absolute;
top: 40px;
left: 0;
background: #ffffff url(images/overlay.png) repeat-x 0 0;
border: solid 1px #b4b4b4;
-webkit-border-radius: 5px;
-moz-border-radius: 5px;
border-radius: 5px;
-webkit-box-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
-moz-box-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
box-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
}
#cssmenu ul ul li {
float: none;
margin: 0;
padding: 3px;
}
#cssmenu ul ul a,
#cssmenu ul ul a:link {
font-weight: normal;
font-size: 12px;
}
#cssmenu ul:after {
content: '.';
display: block;
clear: both;
visibility: hidden;
line-height: 0;
height: 0;
}
* html #cssmenu ul {
height: 1%;
}

Answer 1

I dont think there is a problem, perfectly normal behavior.
There is not enough space in the container, and the last element goes on second line.
If you dont want this to happen, put a min-width:400px; to #cssmenu ul. But since you have couple of ul's inside #cssmenu, better put separate class on the top one.