CSS menu with fly outs - css

Question

I'm trying to create a very basic page of weblinks, arranged into 7 columns. Some of the links have sub-links. What I want to happen is when the mouse is held over a link that has sub-links, the sub-links are to appear just below it and just to the right (as shown in menu 2.2)
I've cobbled the code together from various websites (I'm not a coder!), and I'm almost there I think, but if you take a look at the jsfiddle you will see there is a problem with the 3rd column (I've cut the menu down in the example).
HTML
<div id="container">
<ul id="menu">
<li><h3>Menu 1</h3></li>
<li>1.1</li>
<li>1.2</li>
</ul>
<ul id="menu">
<li><h3>Menu 2</h3></li>
<li>2.1</li>
<li>2.2
<ul id="sub1">
<li>2.2.1</li>
<li>2.2.2</li>
<li>2.2.3</li>
</ul>
</li>
</ul>
<ul id="menu">
<li><h3>Menu 3</h3></li>
<li>3.1
<ul id="sub2">
<li>3.1.1</li>
<li>3.1.2</li>
<li>3.1.3</li>
</ul>
</li>
<li>3.2</li>
<li>3.3</li>
</ul>
CSS
a {
font-family: arial, helvetica, sans-serif;
font-size: 12px;
font-weight: 700;
text-decoration:none;
color:black;
display:block;
padding-top: 17px;
padding-bottom: 17px;
outline: 0;
}
a:visited {
color:black;
background-color:#fff;
}
a:hover {
color:#fff;
background-color:#302403;
display:block;
}
ul {
padding: 10px 0px 0px 0px;
margin: 1px;
display: inline-block;
text-align: center;
position:relative;
list-style-type:none;
float: left;
width: 160px;
background-color: #fff;
height: 400px;
}
ul#sub1 {
position: relative;
left: 30px;
top: -15px;
visibility: hidden;
height: auto;
padding: 0;
}
ul#sub2 {
position: relative;
left: 30px;
top: -15px;
visibility: hidden;
height: auto;
padding: 0;
}
ul#menu li:hover #sub1 {
visibility: visible;
height: auto;
z-index: 1;
border: 2px solid;
padding: 0;
}
ul#menu li:hover #sub2 {
visibility: visible;
height: auto;
z-index: 1;
border: 2px solid;
padding: 0;
}
http://jsfiddle.net/87u27aw0/
I can get it to work if I give each sub-menu it's own absolute position, but I'm sure there is a better way than how I'm doing it - using relative maybe? Oh, and it has to work in IE8 onwards.
Thanks in advance.
Graybags