I have this menu which works fine in firefox etc but just will not work in I.E 7 can anyone tell me why?
<html>
<head>
<title></title>
<style type="text/css">
#mainmenu{
width: auto;
height: 30px;
}
#mainmenu{
margin: 0px;
padding: 0px;
z-index: 1;
}
#mainmenu li{
float:left;
position:relative;
width: 140px;
border: 0px solid #fff;
list-style: none;
background: #336699;
font-family: verdana;
font-weight: bold;
font-size: 14px;
padding: 3px 10px 3px 10px;
}
#mainmenu li a{
background: #336699;
text-decoration: none;
color: #000;
}
#mainmenu li a:hover{
color: #ff0000;
}
#mainmenu li ul{
display:none;
position:absolute;
margin: 0px;
width: 140px;
padding: 0px;
list-style: none;
top: 20px;
left: 0;
z-index: 2;
}
#mainmenu li:hover ul {
display: block;
width: 140px;
}
#mainmenu .drop {
background: #fff;
border-left: 1px solid #000;
border-right: 1px solid #000;
border-bottom: 1px dashed #000;
}
#mainmenu .drop a{
background: #fff;
}
#mainmenu .dropb {
background: #fff;
border-left: 1px solid #000;
border-right: 1px solid #000;
border-bottom: 1px solid #000;
}
#mainmenu .dropb a{
background: #fff;
}
#mainmenu .dropt {
background: #fff;
border-top: 1px solid #000;
border-left: 1px solid #000;
border-right: 1px solid #000;
border-bottom: 1px dashed #000;
}
#mainmenu .dropt a{
background: #fff;
}
</style>
</head>
<body>
<div id="mainmenu">
<li>
<a href="#">MENU 1</a>
<ul>
<li class="dropt"><a href="#">DROP DOWN 1</a></li>
<li class="drop"><a href="#">DROP DOWN 2</a></li>
<li class="dropb"><a href="#">DROP DOWN 3</a></li>
</ul>
</li>
<li>
<a href="#">MENU 2</a>
<ul>
<li><a href="#">DROP DOWN 1</a></li>
<li><a href="#">DROP DOWN 2</a></li>
<li><a href="#">DROP DOWN 3</a></li>
</ul>
</li>
<li>
<a href="#">MENU 3</a>
<ul>
<li><a href="#">DROP DOWN 1</a></li>
<li><a href="#">DROP DOWN 2</a></li>
<li><a href="#">DROP DOWN 3</a></li>
</ul>
</li>
</div>
</body>
</html>