Fluid Width Equal Height Columns

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.

If a design is NON-fluid width, this task becomes considerably easier. The best technique for a fixed width layout 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 to simulate the look of equal height 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.

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, we create gradients with CSS 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%
	);
}

This CSS is applied to a wrapper of all the columns. Because we are using percentages for these color stops, this simulated five-column background-image will stretch and shrink just as you expect it to in a fluid width design. You can think of this as a modern day extension of Faux Columns.

The markup itself is 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 the clearfix class to make 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 your Opera and Older IE visitors will not see the column backgrounds. However, the column structure should remain intact even down to IE 6.

This method allows for source order independence by using negative and positive left margins to jockey columns into position. Here’s a demo of the Doug Neiner method where the column that is first in the source order is moved to 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. These two “columns” have a negative z-index value so they can sit below the visible text content of the column. The third “column” is actually just the background color of the wrapper showing through. Since the height of the wrapper will be set by 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

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 arrange 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 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.

The most significant disadvantage of both table methods 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

Flexbox can handle this situation readily. Here is a reference for all the features and browser support and such.

The markup, again, is perfectly clean:

<div class="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 a few vendor prefixes (or use Autoprefixer) to kick off the flex layout:

.flexbox {
  display: -webkit-flex;
  display: -ms-flexbox;
  display: flex;
  overflow: hidden;
}

From there, we can equalize their widths pretty easily:

.flexbox .col {
  flex: 1;
}

The align-items property can be set to stretch to make sure they are equal height, but that’s the default! So we don’t have to set it at all.

Saving the best for last, we can alter the location of the columns just by setting their order 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 .col:nth-child(1) {
  background: #ccc;
  order: 1;
}
.flexbox .col:nth-child(2) {
  background: #eee;
  order: 0;
}
.flexbox .col:nth-child(3) {
  background: #eee;
  order: 2;
}

JavaScript Options

Of course there are also JavaScript solutions for equal heights columns. We explored that a bit in “Equal Height Blocks in Rows”, and there’s a good CodePen demo by Michah Godbolt that illustrates this method.

If you’d like to go the jQuery plugin route, check out matchHeight, which helps you equalize the height of selected elements.

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.