Fluid Width Equal Height Columns

Published by Chris Coyier

Equal height columns have been a need of web designers forever. If all the columns share the same background, equal height is irrelevant because you can set that background on a parent element. But if one or more columns need to have their own background, it becomes very important to the visual integrity of the design.

THE PROBLEM: Three columns with different amounts of content only grow as tall as they need to individually.


THE DESIRE: Columns are all equally tall, matching the height of the tallest.

If a design is NON-fluid width, this task becomes considerably easier. The best technique to use is Dan Cederholm's Faux Columns where the columns are wrapped in a container element (which you probably already have anyway) and that container has an image background applied to it which repeats vertically and simulates the look of equal heigh columns, even if the elements themselves haven't actually grown.

When fluid width and multiple columns comes into play, this task becomes more difficult. We can no longer use a static image to simulate the look of multiple columns. All hope is not lost though. Below we will investigate a number of different techniques for accomplishing fluid width equal height columns.

View Demo   Download Files

Doug Neiner Method

Doug came up with this on the fly a few month ago during a little nerd chat we had. The idea is to use CSS3 gradients to create the columns. Gradients?! Indeed. We normally think of gradients as a color morphing into another color over distance. However the way we declare gradients with CSS is by declaring "color-stops" which are specific locations where the color will be exactly as specified at that point. The trick is to use overlapping color stops. That way you can get one color to stop and another to begin with no visible "gradient".

Check out how you can get a five-column background, by declaring one color stop at the 0% and 100% mark, and doubles at the 20%/40%/60%/80% marks.

.five-columns { 
	background-image: -webkit-gradient(
		linear,
		left top,
		right top,
		color-stop(0, #eee),
		color-stop(20%, #eee),
		color-stop(20%, #ccc),
		color-stop(40%, #ccc),
		color-stop(40%, #eee),
		color-stop(60%, #eee),
		color-stop(60%, #ccc),
		color-stop(80%, #ccc),
		color-stop(80%, #eee),
		color-stop(100%, #eee)
	);   	
	background-image: -webkit-linear-gradient(
		left, 
		#eee, 
		#eee 20%,
		#ccc 20%,
		#ccc 40%,
		#eee 40%,
		#eee 60%,
		#ccc 60%,
		#ccc 80%,
		#eee 80%,
		#eee 100%
	);
	background-image: -moz-linear-gradient(
		left, 
		#eee, 
		#eee 20%,
		#ccc 20%,
		#ccc 40%,
		#eee 40%,
		#eee 60%,
		#ccc 60%,
		#ccc 80%,
		#eee 80%,
		#eee 100%
	);
	background-image: -ms-linear-gradient(
		left, 
		#eee, 
		#eee 20%,
		#ccc 20%,
		#ccc 40%,
		#eee 40%,
		#eee 60%,
		#ccc 60%,
		#ccc 80%,
		#eee 80%,
		#eee 100%
	);
	background-image: -o-linear-gradient(
		left, 
		#eee, 
		#eee 20%,
		#ccc 20%,
		#ccc 40%,
		#eee 40%,
		#eee 60%,
		#ccc 60%,
		#ccc 80%,
		#eee 80%,
		#eee 100%
	);
}

Because we are using percentages for these color stops, this simulated five-column background-image will stretch and shrink just as you expect them to in a fluid width design. This CSS would be applied to to individual columns, but to a wrapper of all the columns. You can think of it as a modern day extension of Faux Columns. The markup itself would then just be a series of columns inside that wrapper.

<div class="five-columns group">

	<div class="col"><p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas.</p></div>
	<div class="col"><p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p></div>
	<div class="col"><p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas.</p></div>
	<div class="col"><p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p></div>
	<div class="col"><p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas.</p></div>

</div>

Notice the "group" class which is just the clearfix class so that the parent wrapper retains its height despite containing only floated children (it would normally collapse).

I think this is a rather clever take on the idea. Do note that that only modern Gecko and WebKit browsers support CSS3 gradients so you're Opera and IE visitors will not see the column backgrounds. However, the column structure should remain intact just fine even down to IE 6.

This method allows for source order independence by using negative and positive left margins where necessary to jockey columns into position. See the demo for an example of the Doug Neiner method including putting the first column source order wise into the middle.

Nicolas Gallagher Method

Nicolas Gallagher published a gem of an article about using CSS2 pseudo elements to achieve a number of effects that are otherwise difficult to pull off or that require additional HTML clutter.

The idea is to set the parent wrapper with relative positioning. This sets the context for absolute positioning within. Then we make each of three columns one-third the width of the parent and position them relatively within, pushing them over with relative positioning as needed. This also allows for source order independence.

Two of the visible background coloration columns are generated by absolutely positioned block-level pseudo elements (:before and :after) which are again one-third of the width, but 100% of the height of the parent. They are able to sit below the visible text content of the column by having a negative z-index value. The third "column" is actually just the background color of the wrapper showing through. Since the height of the wrapper will be the height of the tallest column, this works.

.pseudo-three-col {
	position: relative; 
	background: #eee; 
	z-index: 1; 
	width: 100%; 
}
.pseudo-three-col .col { 
	position: relative; 
	width: 27%; 
	padding: 3%; 
	float: left; 
}
.pseudo-three-col .col:nth-child(1) { left: 33%; }
.pseudo-three-col .col:nth-child(2) { left: -33.3%; }
.pseudo-three-col .col:nth-child(3) { left: 0; }
.pseudo-three-col:before, .pseudo-three-col:after {
   content: " ";
   position: absolute;
   z-index: -1;
   top: 0;
   left: 33.4%;
   width: 33.4%;
   height: 100%;
   background: #ccc;
}
.pseudo-three-col:after {
   left: 66.667%;
   background: #eee;
}

Using Tables

I bet some of you are starting to think like this by this time. Hey, I don't blame you. Sometimes a tried and true method that gets the job done is the way to go. One way to sure-fire accomplish the idea of fluid width equal height columns is a dang ol' row of table cells. Just in case you forgot how that looks, it's like this:

<table id="actual-table">
	<tr>
		<td>
			<p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas.</p>
		</td>
		<td>
			<p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p>
		</td>
		<td>
			<p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas.</p>
		</td>
		<td>
			<p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p>
		</td>
		<td>
			<p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas.</p>
		</td>
	</tr>
</table>

Give each table cell a percentage width that totals up to 100% and you'll be set. Even if you then apply padding to the cells, the table will jockey itself correctly.

#actual-table { border-collapse: collapse; }
#actual-table td { 
	width: 20%; 
	padding: 10px; 
	vertical-align: top;
}
#actual-table td:nth-child(even) { 
	background: #ccc;
}
#actual-table td:nth-child(odd) { 
	background: #eee;
}

Now let's say that table markup gives you the heebie-jeebies. You can actually use plain ol' div markup if you want but still force it to behave like a table. In that case we'd do something like this:

<div id="css-table">
	<div class="col"><p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas.</p></div>
	<div class="col"><p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p></div>
	<div class="col"><p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas.</p></div>
	<div class="col"><p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p></div>
</div>

And then use CSS tables:

#css-table { 
	display: table; 
}
#css-table .col { 
	display: table-cell; 
	width: 25%; 
	padding: 10px; 
}
#css-table .col:nth-child(even) { 
	background: #ccc;
}
#css-table .col:nth-child(odd) { 
	background: #eee;
}

Besides using comfortable markup, we actually save some markup because we can go right from the table to the table cells. No element needs to simulate a table-row.

So are CSS tables the answer to our dreams? They are kinda cool, but they aren't supported in IE 7 so if you are interested in going this route I'd recommend just using actual table markup instead. There is really no significant advantages to using CSS tables.

Both of these methods most significant disadvantage is source-order dependance. There is really no way to have the first column in the source order appear anywhere else than the first column.

One True Layout Method

One of the most classic layouts of all time is the one true layout. In one of the demos, equal height columns is tackled. It's a rather clever technique that still works great today. The idea, as usual, uses a wrapping element for all the columns. This wrapper is set to have hidden overflow, which not only clears the floated columns, but hides anything sticking outside of it. This is particularly important, because we are going to be forcing the height of the columns to be extremely tall, and then cutting them off with the hidden overflow. The magical voodoo here is that while we force the columns taller with a huge amount of bottom padding, we suck the height of the wrapper back up with an equal amount of negative bottom margin. This gives us just the effect we need.

The markup is nothing we haven't seen before:

<div id="one-true" class="group">
	<div class="col"><h3>I am listed first in source order.</h3><p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas.</p></div>
	<div class="col"><p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p></div>
	<div class="col"><p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas.</p></div>
</div>

Then the CSS is just floated columns with the margin/padding trick.

#one-true { overflow: hidden; }
#one-true .col {
	width: 27%;
	padding: 30px 3.15% 0; 
	float: left;
	margin-bottom: -99999px;
	padding-bottom: 99999px;
}
#one-true .col:nth-child(1) { margin-left: 33.3%; background: #ccc; }
#one-true .col:nth-child(2) { margin-left: -66.3%; background: #eee; }
#one-true .col:nth-child(3) { left: 0; background: #eee; }
#one-true p { margin-bottom: 30px; } /* Bottom padding on col is busy */

Note that the padding on the bottoms of the columns is generated by the content within pushing down, as we can't count on bottom padding on the column itself, as it's busy with its fancy trick. Source order independence here is just like we've already covered, with jockeying around with left margins.

Flexbox Method

CSS3 brings with it the flexible box model. Paul Irish recently blogged about it on HTML5 Rocks. Browser support for this is limited at the time of this writing to WebKit only. Mozilla is kind of supporting it, but all the demos I ever see are of images or very little text. As soon as lots of wrapping text gets involved Firefox falls apart. Here is an example that works great in WebKit and fails in Firefox.

The markup, again, is perfectly clean:

<div id="flexbox">

	<div class="col"><h3>I am listed first in source order.</h3><p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas.</p></div>
	<div class="col"><p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p></div>
	<div class="col"><p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas.</p></div>

</div>

The CSS requires, unsurprisingly, a variety of vendor prefixes to kick off the flexible box model. From there, we set the columns widths and padding, but do not require floats. Telling the box orientation to be horizontal is what gets us the layout we want. We then align the columns vertically setting both box-pack and box-align to start.

The flexible box model does not have any methods for forcing the internal boxes to be of equal height. Most of the demos you will see look like they are, but that's because a height is being explicitly set. Because we are hoping for dynamic height columns, we'll have to borrow from the One True Layout and using the positive/negative padding/margin idea.

Finally, saving the best for last, we can alter the location of the columns just by setting their box-ordinal-group to the desired location. It's best to explicitly set all columns where you want them to be, I found setting only certain ones was problematic. Still, being able to change location without layout hacks is awesome.

#flexbox {		
  display: -webkit-box;
  -webkit-box-orient: horizontal;
  -webkit-box-pack: start;
  -webkit-box-align: start;
	
  display: -moz-box;
  -moz-box-orient: horizontal;
  -moz-box-pack: start;
  -moz-box-align: start;
	
  display: box;
  box-orient: horizontal;
  box-pack: start;
  box-align: start;
	
  overflow: hidden;
}
#flexbox .col {
  width: 27.333%;
  padding: 30px 3% 0;
	
  margin-bottom: -99999px;
  padding-bottom: 99999px;
}
#flexbox .col p {
  margin-bottom: 30px;
}
#flexbox .col:nth-child(1) {
  -moz-box-ordinal-group: 2;
  -webkit-box-ordinal-group: 2;
  box-ordinal-group: 2;
  background: #ccc;
}
#flexbox .col:nth-child(2) {
  -moz-box-ordinal-group: 1;
  -webkit-box-ordinal-group: 1;
  box-ordinal-group: 1;
  background: #eee;
}
#flexbox .col:nth-child(3) {
  -moz-box-ordinal-group: 3;
  -webkit-box-ordinal-group: 3;
  box-ordinal-group: 3;
  background: #eee;
}
The flexbox stuff shown here is a bit old. There is a new syntax available. See The Complete Guide to Flexbox.

Quick Notes

  • Using percentages for layout isn't perfect in WebKit
  • In this demo I used things like :nth-child to target some columns. You'll likely get better cross browser compatibility if you give your columns specific class names and use those class names instead. I was more interested in investigating the theory here, and some of the fancy modern techniques only work in browsers where :nth-child would work anyway.
  • Bonus tip: you can use a Faux Columns-like technique with fluid width columns if you only have two columns. This is in use on the current (v7) design of CSS-Tricks. The layout is 2-column fluid, and the background color of the sidebar comes from this image. The column is able to grow, because the placement of that background uses percentages to get it to adjust correctly as the container element grows in width.
    background: url(sidebar.png) repeat-y 61.7% 0;
  • Flexible layout model is very different from the CSS3 layout module. Apparently the wind is blowing toward flexible layout as far as actual implementation.

 

View Demo   Download Files