@charset "UTF-8";
/* CSS Document */

<ul id="sddm">
    <li><a href="#" 
        onmouseover="mopen('m1')" 
        onmouseout="mclosetime()">Home</a>
        <div id="m1" 
            onmouseover="mcancelclosetime()" 
            onmouseout="mclosetime()">
        <a href="#">HTML Drop Down</a>
        <a href="#">DHTML Menu</a>
        <a href="#">JavaScript DropDown</a>
        <a href="#">Cascading Menu</a>
        <a href="#">CSS Horizontal Menu</a>
        </div>
    </li>
    <li><a href="#" 
        onmouseover="mopen('m2')" 
        onmouseout="mclosetime()">Download</a>
        <div id="m2" 
            onmouseover="mcancelclosetime()" 
            onmouseout="mclosetime()">
        <a href="#">ASP Dropdown</a>
        <a href="#">Pulldown menu</a>
        <a href="#">AJAX Drop Submenu</a>
        <a href="#">DIV Cascading Menu</a>
        </div>
    </li>
    <li><a href="#">Order</a></li>
    <li><a href="#">Help</a></li>
    <li><a href="#">Contact</a></li>
</ul>
<div style="clear:both"></div>
CSS Code
<li> tag have loat: left; declaration. sumbmenu layer have visibility: hidden; and position: absolute;. Anchor tag set to display: block;
Everything else is usual decoration:
#sddm
{	margin: 0;
	padding: 0;
	z-index: 30}

#sddm li
{	margin: 0;
	padding: 0;
	list-style: none;
	float: left;
	font: bold 11px arial}

#sddm li a
{	display: block;
	margin: 0 0px 0 0;
	padding: 4px 10px;
	width: 70px;
	background: #ebebeb;
	color: #09185b;
	text-align: center;
	text-decoration: none}

#sddm li a:hover
{	background: #9197b9;
	color: #FFF;}

#sddm div
{	position: absolute;
	left: 0;
	top: 0;
	visibility: hidden;
	margin: 0;
	padding: 0;
	background: #ebebeb;
	border: 1px solid #5970B2}

	#sddm div a
	{	position: relative;
		display: block;
		margin: 0;
		padding: 4px 10px;
		width: 70;
		white-space: nowrap;
		text-align: left;
		text-decoration: none;
		background: #ebebeb;
		color: #09185b;
		font: 11px arial}

	#sddm div a:hover
	{	background: #9197b9;
		color: #FFF}