Creating Tabs That Behave

Chris Coyier //

When creating navigational tabs that use real web text, some positioning issues may arise when that text is resized. The natural flow of a web page when text is resized is to push down. This can push your main content area down and/or force the tabs into that area. Using some smart CSS, we can fix this issue by creating tabs that grow upward when text is resized.

Bad Example

View Bad Example

In this example of bad tab behavior, when text is resized the tabs grow downward and push into the main content area.

One solution could be to have the tabs push down the main content area as they grow. In this example that may be fine, but that may be unacceptable for a more image-based design or for folks nervous about losing content below the "fold".

Good Example

View Good Example

In our good example, the main content area stays put. The tabs grow upward and the rest of the text grows downward as usual.

The Trick

The meat of the trick is using two nested block level elements. The outside block controls the positioning. We need to lock to the top of the main content, so the outside block needs top: 0;. The inside block then sticks to the bottom of the outside block with absolute positioning. By setting a fixed bottom value, bottom: 0;, the menu items have no where to grow but up.

Menu markup:

<div id="nav">
		<li><a href="#">Tab 4</a></li>
		<li><a href="#">Tab 3</a></li>
		<li><a href="#">Tab 2</a></li>
		<li><a href="#">Tab 1</a></li>

Code purists will notice right away the common folly of wrapping an unordered list in a div unnecessarily. In our case though, it is very necessary, and we need both of those block level elements for our trick.

CSS for the two blocks:

#nav	 { 
   position: absolute;
   left: 0; 
   top: 0; 
   width: 100%; 
   height: 0;
#nav ul { 
   position: absolute; 
   bottom: 0; 
   right: 0; 

Here is a visual:


This is becoming less and less of an issue as more browsers are using full zoom instead of straight text resizing. But still, it's just good responsible design at this time.