Untitled

Creating a three-column navigation menu. Having trouble with valid structuring that allows independent scrolling
<ul class="all departments">
    <li class="first department">
        <ul class="all courses in department">
            <li class="first course">
                <ul class="all sections on course">
                  <li class="first section"></li>
                </ul>
            </li>
        </ul>
    </li>
</ul>

div.columncont
{
 height: 500px;
 width: 600px;
}
div.column
{
 width: 200px;
 float: left;
 height: 100%;
 overflow-y: scroll;
}