CSSnewbie

Attractive dropdown menus have long been the realm of Flash developers and advanced JavaScript gurus. But that needn’t be the case. This tutorial will walk you through developing a clean, semantic dropdown menu using XHTML and CSS that works in all modern browsers!

Let’s start with the XHTML first and foremost. It’s surprisingly simple:

<ul id="navbar">
	<li><a href="#">Item One</a><ul>
		<li><a href="#">Subitem One</a></li>
		<li><a href="#">Second Subitem</a></li>
		<li><a href="#">Numero Tres</a></li></ul>
	</li>
	<!-- ... and so on ... -->
</ul>

As you can see, our navigation bar consists of nested unordered lists and anchor tags. The key to this working correctly is to properly nest your unordered lists, wrapping the list item around the unordered list that is nested under it (for more on that topic, see this article on styling nested lists). The main list items will be our main navigation bar, while the nested unordered lists will become our subnavigation elements. The navigation bar also works without submenus, so you can mix and match as needs be. Also note that, other than an ID on our primary containing unordered list, there are no additional classes or IDs required!

Next, we’ll start adding a few styles to our navigation bar:

#navbar {
	margin: 0;
	padding: 0;
	height: 1em; }
#navbar li {
	list-style: none;
	float: left; }
#navbar li a {
	display: block;
	padding: 3px 8px;
	background-color: #5e8ce9;
	color: #fff;
	text-decoration: none; }

Here, I’ve removed the margin and padding from the main list, removed all list styling from all the list items, and floated the individual items left. I’ve also added a bit of styling to the anchors, just to make it look a little more like a navigation bar. As you can see, this really isn’t any different than making any other sort of navigation bar to start out with.

The only real oddity here is the “height: 1em;” rule on the navbar ID: this forces the navbar to have a specific height (1em) and width (100% by default), meaning I don’t have to do anything special to “clear” the navigation afterwards. Without that rule, I’d generally need to apply a “clear: left;” to whatever came immediately after the navigation to prevent it from trying to fill the space voided by those left-floated list items. The actual height is arbitrary: as long as a height is specified, the list will retain its block-level status.

Next, we can apply some styles to the subnavigation section:

#navbar li ul {
	display: none;
	width: 10em; /* Width to help Opera out */
	background-color: #69f;}

This is pretty straightforward: we’re applying a display: none to prevent the submenu from displaying by default, and giving it a background color to make it stand out against the background. The only odd bit is the width property, which is mostly there to prevent Opera from doing some weird things with the width of the submenus (Opera makes them strangely small without a width specified). However, it also ads a nice bit of consistency to the submenus, so I don’t really mind the “fix.” I chose 10em because that allowed all of my submenu items to exist on one line, but you could choose whatever size works for you.

Now all we need to do is style the list for its “hover” state:

#navbar li:hover ul {
	display: block;
	position: absolute;
	margin: 0;
	padding: 0; }
#navbar li:hover li {
	float: none; }
#navbar li:hover li a {
	background-color: #69f;
	border-bottom: 1px solid #fff;
	color: #000; }
#navbar li li a:hover {
	background-color: #8db3ff; }

Let’s go through this bit by bit. The first rule causes the submenu to reappear when the user hovers over the containing list item (this is where the properly nested lists come in handy). We’re using position: absolute on the menus to ensure they don’t push any content below the navigation out of the way. The margin and padding are simply getting rid of the default spacing on the lists so we can style them ourselves.

Next up comes the “float: none” rule on the list items. This is just preventing the items in the submenu from floating left: it’s counteracting our previous “float: left” rule so that our submenu doesn’t mimic our main navigation elements.

The rules we’re applying to “#navbar li:hover li a” are purely stylistic: I’m applying a background color, bottom border, and changing the color of the anchor. You could set these to be anything you wanted whatsoever.

And finally, I’m applying a different background color to the anchor when it’s being hovered over, just to help set it apart from the other items in the list. This is to improve usability: the user can easily see which item their cursor is over.

That’s all it takes! You can see a working example here. I’ve tested this and found it working in Firefox 2, IE7, Opera 8.5+, and Safari for Windows. Of course, you’ll note that I’m leaving out the usual party pooper: Internet Explorer 6. Because of IE6’s limitations on :hover states (you can only hover over anchors in IE6, instead of any element like in all the other browsers), this fantastic little technique doesn’t work. Unless, of course, you’re willing to add in a couple of lines of JavaScript.

The brilliant hive mind that is Patrick Griffiths and Dan Webb have come up with a fantastic JavaScript solution for Internet Explorer that solves the :hover problem in just 12 lines of code. The version I’m using looks like this:

sfHover = function() {
	var sfEls = document.getElementById("navbar").getElementsByTagName("li");
	for (var i=0; i<sfEls.length; i++) {
		sfEls[i].onmouseover=function() {
			this.className+=" hover";
		}
		sfEls[i].onmouseout=function() {
			this.className=this.className.replace(new RegExp(" hover\\b"), "");
		}
	}
}
if (window.attachEvent) window.attachEvent("onload", sfHover);

The concept is pretty brilliantly simple (even if the code looks complex). The function goes through your document and finds every list item contained within the “navbar” id (you could change this to be whatever you wanted). It then applies a “mouseover” and “mouseout” state on every item: it adds a class of “hover” to the list item whenever it’s being moused over, and removes it when the cursor wanders off. The result is you can then apply your CSS to the .hover class as well as the :hover pseudo-class and create identical results across the board. So all you need to do is modify your CSS like so:

#navbar li:hover ul, #navbar li.hover ul {
	display: block;
	position: absolute;
	margin: 0;
	padding: 0; }
#navbar li:hover li, #navbar li.hover li {
	float: none; }
#navbar li:hover li a, #navbar li.hover li a {
	background-color: #69f;
	border-bottom: 1px solid #fff;
	color: #000; }

And that’s it! With just three tiny changes to your CSS and a dozen lines of JavaScript, you have a CSS dropdown solution that works on every single modern browser – even the ones that aren’t exactly standards-compliant.