我正在写一个网站atm，现在我们有一个子菜单放在主菜单下面的一行。但是如果你把主菜单放在主菜上，我们决定制作一个可以折叠的子菜单。在此处http://www.nvidia.de/page/home.html
<!-- main-menu start -->
<div id="menu">
<ul class="menu">
<li><a href="index.html"><span>Home</span></a></li>
<li><a class="active" href="events.html"><span>Events</span></a></li>
<ul> <li> <a class="submenu" href="#"> Umfrage </a> </li> </ul>
<li><a href="galerie.html"><span>Galerie</span></a></li>
<li><a href="locations.html"><span>Locations</span></a></li>
<li><a href="tanzschulen.html"><span>Tanzschulen</span></a></li>
<li><a href="festivals.html"><span>Festivals</span></a></li>
<li><a href="reisen.html"><span>Reisen</span></a></li>
<li><a href="community.html"><span>Community</span></a></li>
</ul>
</div>
<!-- main-menu end -->
<!-- sub-menu start -->
<script type="text/javascript">
function openwindow() {
window.open ("./loginpage.php","openwindowname","width=350,height=150,scrollbars=no,resizable=no,toolbar=no,location=no,directories=no,status=no,menu bar=no,copyhistory=no,");
}
function closewindow() {
window.close()
}
</script>
<div id="submenu">
<ul class="submenu">
<li><a href="#">Umfragen</a></li>
<li class="login-logout"><a href="registrieren.html">Registrieren</a> | <a href ="#openModal">Login</a></li>
<div id="openModal" class="modalDialog">
<div>
<a href="#close" title="Close" class="close">X</a>
<h2>Login</h2>
<form action="">
<table border="0" cellpadding="3" cellspacing="0">
<tr><td class="first">E-Mail</td><td><input name="name" type="text" size="30" placeholder="E-Mail"></td></tr>
<tr><td class="first">Passwort</td><td><input name="email" type="text" size="30" placeholder="Passwort"></td></tr>
<td class="col_1 col_last"><div style="margin-top: 12px" class="checkbox_container"><input type="checkbox" name="autologin" id="autologin" value="1" class="checkbox"> <label for="autologin">Angemeldet bleiben</label></div></td>
</tr>
</table>
</form>
<div class="send-button2">
<label class="party ui-button ui-widget ui-state-default ui-button-text-only ui-corner-left" role="button"><span class="ui-button-text"><a href="#close" title="Close">Login</a></span></label>
</div>
</div>
</div>
</ul>
</div>
<!-- sub-menu end -->