I have a horizontal menu as an unordered list:
<form id="MainForm" runat="server">
    <h1>Main Form</h1>
    <div>
        <ul class="nav">
            <li><a href="/WebForm1.aspx">Form 1</a></li>
            <li><a href="/WebForm2.aspx">Form 2</a></li>
            <li><a href="/WebForm3.aspx">Form 3</a></li>
        </ul>
    </div>
</form>
From my external .css:
ul.nav {
    padding-left: 0px;
    background-color: #3D99CE;
    text-align: left;
}
ul.nav > li {
    display: inline-block;
    padding: 10px 10px;
    height: 10px;
}
ul.nav > li:hover {
    background-color: #2779BF;
}
ul.nav > li > a {
    color: white;
    text-decoration: none;
}
I would like another list item in the horizontal list that has a dropdown list that would serve as submenu items that do not show until I click the horizontal menu item. How can I achieve that?
I suspect the magic will be in the style sheet.
Thank you.