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CSS CSS Layout Techniques Float Layout The Float Clearfix

Fabrício Montenegro
Fabrício Montenegro
18,722 Points
Posted by Fabrício Montenegro
Fabrício Montenegro
18,722 Points

Explain clearfix

In this lesson we are told that we can use some css to fix the collapsing problem when an element .group has floating children. This is the code:

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

Now, I don't really get it. What does it do? I know ::after will insert a pseudo-element after the .group element, but how an element outside the parent will clear its children? And why does it have a display: table;? I know it works and I could use it from now on but I really wanna understand how it works.

2 Answers

Jason Anello
Jason Anello
Courses Plus Student 94,610 Points

Hi Fabricio,

::after doesn't insert content after the .group element but rather at the very end of the element before the closing tag. This mdn page, ::after (:after), refers to it as matching a virtual last child.

So the idea is that you're inserting invisible content as the last child of a parent. Since this generated content clears the floats it will drop below all previously floated elements. Since this generated content is not floated itself, the parent element must expand all the way down to contain it. Automatically containing all the floated children that came before.

Fabrício Montenegro
Fabrício Montenegro
18,722 Points
Fabrício Montenegro
Fabrício Montenegro
18,722 Points

Wow, my life was a lie! Thanks for clearing out what :after actually does. Your explanation was pretty good. :D

But how about the table display?

Jason Anello
Jason Anello
Courses Plus Student 94,610 Points

Also, you might see older markup like this:

<div class="container">
    <p>Some paragraph that has been floated left</p>
    <div style="clear: both"></div>
</div>

This empty div at the end is acting as the clearing element which causes the "container" div to contain the floated paragraph. This works but your markup is now cluttered with an empty div which is only there for presentational reasons.

The clearfix technique is a replacement for this. It does the same thing and allows us to keep content and presentation separate.

Jason Anello
Jason Anello
Courses Plus Student 94,610 Points

This link should help with explanations of the properties used like table

A new micro clearfix hack

Jason Anello
Jason Anello
Courses Plus Student 94,610 Points

You're welcome!