What methods of ‘clearfix’ can I use?

What problems are we trying to solve?

There are two important considerations when floating stuff:

  1. Containing descendant floats. This means that the element in question makes itself tall enough to wrap all floating descendants. (They don't hang outside.)

    Floating content hanging outside its container

  2. Insulating descendants from outside floats. This means that descendants inside of an element should be able to use clear: both and have it not interact with floats outside the element.

    <code>clear: both</code> interacting with a float elsewhere in the DOM

Block formatting contexts

There's only one way to do both of these. And that is to establish a new block formatting context. Elements that establish a block formatting context are an insulated rectangle in which floats interact with each other. A block formatting context will always be tall enough to visually wrap its floating descendants, and no floats outside of a block formatting context may interact with elements inside. This two-way insulation is exactly what you want. In IE, this same concept is called hasLayout, which can be set via zoom: 1.

There are several ways to establish a block formatting context, but the solution I recommend is display: inline-block with width: 100%. (Of course, there are the usual caveats with using width: 100%, so use box-sizing: border-box or put padding, margin, and border on a different element.)

The most robust solution

Probably the most common application of floats is the two-column layout. (Can be extended to three columns.)

First the markup structure.

<div class="container">
  <div class="sidebar">
    sidebar<br/>sidebar<br/>sidebar
  </div>
  <div class="main">
    <div class="main-content">
      main content
      <span style="clear: both">
        main content that uses <code>clear: both</code>
      </span>
    </div>
  </div>
</div>

And now the CSS.

/* Should contain all floated and non-floated content, so it needs to
 * establish a new block formatting context without using overflow: hidden.
 */
.container {
  display: inline-block;
  width: 100%;
  zoom: 1; /* new block formatting context via hasLayout for IE 6/7 */
}

/* Fixed-width floated sidebar. */
.sidebar {
  float: left;
  width: 160px;
}

/* Needs to make space for the sidebar. */
.main {
  margin-left: 160px;
}

/* Establishes a new block formatting context to insulate descendants from
 * the floating sidebar. */
.main-content {
  display: inline-block;
  width: 100%;
  zoom: 1; /* new block formatting context via hasLayout for IE 6/7 */
}

Try it yourself

Go to JS Bin to play around with the code and see how this solution is built from the ground up.

Traditional clearfix methods considered harmful

The problem with the traditional clearfix solutions is that they use two different rendering concepts to achieve the same goal for IE and everyone else. In IE they use hasLayout to establish a new block formatting context, but for everyone else they use generated boxes (:after) with clear: both, which does not establish a new block formatting context. This means things won't behave the same in all situations. For an explanation of why this is bad, see Everything you Know about Clearfix is Wrong.


Depending upon the design being produced, each of the below clearfix CSS solutions has its own benefits.

The clearfix does have useful applications but it has also been used as a hack. Before you use a clearfix perhaps these modern css solutions can be useful:

  • css flexbox
  • css grid

Modern Clearfix Solutions

Container with overflow: auto;

The simplest way to clear floated elements is using the style overflow: auto on the containing element. This solution works in every modern browsers.

<div style="overflow: auto;">
  <img
    style="float: right;"
    src="path/to/floated-element.png"
    width="500"
    height="500"
  > 
  <p>Your content here…</p>
</div>

One downside, using certain combinations of margin and padding on the external element can cause scrollbars to appear but this can be solved by placing the margin and padding on another parent containing element.

Using ‘overflow: hidden’ is also a clearfix solution, but will not have scrollbars, however using hidden will crop any content positioned outside of the containing element.

Note: The floated element is an img tag in this example, but could be any html element.

Clearfix Reloaded

Thierry Koblentz on CSSMojo wrote: The very latest clearfix reloaded. He noted that by dropping support for oldIE, the solution can be simplified to one css statement. Additionally, using display: block (instead of display: table) allows margins to collapse properly when elements with clearfix are siblings.

.container::after {
  content: "";
  display: block;
  clear: both;
}

This is the most modern version of the clearfix.

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Older Clearfix Solutions

The below solutions are not necessary for modern browsers, but may be useful for targeting older browsers.

Note that these solutions rely upon browser bugs and therefore should be used only if none of the above solutions work for you.

They are listed roughly in chronological order.

"Beat That ClearFix", a clearfix for modern browsers

Thierry Koblentz' of CSS Mojo has pointed out that when targeting modern browsers, we can now drop the zoom and ::before property/values and simply use:

.container::after {
    content: "";
    display: table;
    clear: both;
}

This solution does not support for IE 6/7 …on purpose!

Thierry also offers: "A word of caution: if you start a new project from scratch, go for it, but don’t swap this technique with the one you have now, because even though you do not support oldIE, your existing rules prevent collapsing margins."

Micro Clearfix

The most recent and globally adopted clearfix solution, the Micro Clearfix by Nicolas Gallagher.

Known support: Firefox 3.5+, Safari 4+, Chrome, Opera 9+, IE 6+

.container::before, .container::after {
  content: "";
  display: table;
}
.container::after {
  clear: both;
}
.container {
  zoom: 1;
}

Overflow Property

This basic method is preferred for the usual case, when positioned content will not show outside the bounds of the container.

http://www.quirksmode.org/css/clearing.html - explains how to resolve common issues related to this technique, namely, setting width: 100% on the container.

.container {
  overflow: hidden;
  display: inline-block;
  display: block;
}

Rather than using the display property to set "hasLayout" for IE, other properties can be used for triggering "hasLayout" for an element.

.container {
  overflow: hidden;
  zoom: 1;
  display: block;
}

Another way to clear floats using the overflow property is to use the underscore hack. IE will apply the values prefixed with the underscore, other browsers will not. The zoom property triggers hasLayout in IE:

.container {
  overflow: hidden;
  _overflow: visible; /* for IE */
  _zoom: 1; /* for IE */
}

While this works... it is not ideal to use hacks.

PIE: Easy Clearing Method

This older "Easy Clearing" method has the advantage of allowing positioned elements to hang outside the bounds of the container, at the expense of more tricky CSS.

This solution is quite old, but you can learn all about Easy Clearing on Position Is Everything: http://www.positioniseverything.net/easyclearing.html

Element using "clear" property

The quick and dirty solution (with some drawbacks) for when you’re quickly slapping something together:

<br style="clear: both" /> <!-- So dirty! -->

Drawbacks

  • It's not responsive and thus may not provide the desired effect if layout styles change based upon media queries. A solution in pure CSS is more ideal.
  • It adds html markup without necessarily adding any semantic value.
  • It requires a inline definition and solution for each instance rather than a class reference to a single solution of a “clearfix” in the css and class references to it in the html.
  • It makes code difficult to work with for others as they may have to write more hacks to work around it.
  • In the future when you need/want to use another clearfix solution, you won't have to go back and remove every <br style="clear: both" /> tag littered around the markup.

Tags:

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