Why doesn t the height of a container element increase if it contains floated elements

Question

I would like to ask how height and float work  I have an outer div and an inner div that has content in it  Its height may vary depending on the content of the inner div but it seems that my inner div will overflow its outside div  What would be the proper way to do it    x000D   x000D    lt html gt  x000D       lt body gt  x000D           lt div style  margin 0 auto width  960px  min-height  100px  background-color orange  gt  x000D            lt div style  width 500px  height 200px  background-color black  float right  gt  lt  div gt  x000D           lt  div gt  x000D       lt  body gt  x000D   lt  html gt  x000D   x000D   x000D

User · Accepted Answer

The floated elements do not add to the height of the container element, and hence if you don't clear them, container height won't increase...

I'll show you visually:

enter image description here

More Explanation:

<div>
  <div style="float: left;"></div>
  <div style="width: 15px;"></div> <!-- This will shift 
                                        besides the top div. Why? Because of the top div 
                                        is floated left, making the 
                                        rest of the space blank -->

  <div style="clear: both;"></div> 
  <!-- Now in order to prevent the next div from floating beside the top ones, 
       we use `clear: both;`. This is like a wall, so now none of the div's 
       will be floated after this point. The container height will now also include the 
       height of these floated divs -->
  <div></div>
</div>

You can also add overflow: hidden; on container elements, but I would suggest you use clear: both; instead.

Also if you might like to self-clear an element you can use

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

How Does CSS Float Work?

What is float exactly and what does it do?

The float property is misunderstood by most beginners. Well, what exactly does float do? Initially, the float property was introduced to flow text around images, which are floated left or right. Here's another explanation by @Madara Uchicha.
So, is it wrong to use the float property for placing boxes side by side? The answer is no; there is no problem if you use the float property in order to set boxes side by side.
Floating an inline or block level element will make the element behave like an inline-block element.
Demo
If you float an element left or right, the width of the element will be limited to the content it holds, unless width is defined explicitly ...
You cannot float an element center. This is the biggest issue I've always seen with beginners, using ~~float: center;~~, which is not a valid value for the float property. float is generally used to float/move content to the very left or to the very right. There are only four valid values for float property i.e left, right, none (default) and inherit.
Parent element collapses, when it contains floated child elements, in order to prevent this, we use clear: both; property, to clear the floated elements on both the sides, which will prevent the collapsing of the parent element. For more information, you can refer my another answer here.
(Important) Think of it where we have a stack of various elements. When we use float: left; or float: right; the element moves above the stack by one. Hence the elements in the normal document flow will hide behind the floated elements because it is on stack level above the normal floated elements. (Please don't relate this to z-index as that is completely different.)

Taking a case as an example to explain how CSS floats work, assuming we need a simple 2 column layout with a header, footer, and 2 columns, so here is what the blueprint looks like...

enter image description here

In the above example, we will be floating only the red boxes, either you can float both to the left, or you can float on to left, and another to right as well, depends on the layout, if it's 3 columns, you may float 2 columns to left where another one to the right so depends, though in this example, we have a simplified 2 column layout so will float one to left and the other to the right.

Markup and styles for creating the layout explained further down...

<div class="main_wrap">
    <header>Header</header>
    <div class="wrapper clear">
        <div class="floated_left">
            This<br />
            is<br />
            just<br />
            a<br />
            left<br />
            floated<br />
            column<br />
        </div>
        <div class="floated_right">
            This<br />
            is<br />
            just<br />
            a<br />
            right<br />
            floated<br />
            column<br />
        </div>
    </div>
    <footer>Footer</footer>
</div>

* {
    -moz-box-sizing: border-box;       /* Just for demo purpose */
    -webkkit-box-sizing: border-box;   /* Just for demo purpose */
    box-sizing: border-box;            /* Just for demo purpose */
    margin: 0;
    padding: 0;
}

.main_wrap {
    margin: 20px;
    border: 3px solid black;
    width: 520px;
}

header, footer {
    height: 50px;
    border: 3px solid silver;
    text-align: center;
    line-height: 50px;
}

.wrapper {
    border: 3px solid green;
}

.floated_left {
    float: left;
    width: 200px;
    border: 3px solid red;
}

.floated_right {
    float: right;
    width: 300px;
    border: 3px solid red;
}

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

Let's go step by step with the layout and see how float works..

First of all, we use the main wrapper element, you can just assume that it's your viewport, then we use header and assign a height of 50px so nothing fancy there. It's just a normal non floated block level element which will take up 100% horizontal space unless it's floated or we assign inline-block to it.

The first valid value for float is left so in our example, we use float: left; for .floated_left, so we intend to float a block to the left of our container element.

Column floated to the left

And yes, if you see, the parent element, which is .wrapper is collapsed, the one you see with a green border didn't expand, but it should right? Will come back to that in a while, for now, we have got a column floated to left.

Coming to the second column, lets it float this one to the right

Another column floated to the right

Here, we have a 300px wide column which we float to the right, which will sit beside the first column as it's floated to the left, and since it's floated to the left, it created empty gutter to the right, and since there was ample of space on the right, our right floated element sat perfectly beside the left one.

Still, the parent element is collapsed, well, let's fix that now. There are many ways to prevent the parent element from getting collapsed.

Add an empty block level element and use clear: both; before the parent element ends, which holds floated elements, now this one is a cheap solution to clear your floating elements which will do the job for you but, I would recommend not to use this.

Add, <div style="clear: both;"></div> before the .wrapper div ends, like

<div class="wrapper clear">
    <!-- Floated columns -->
    <div style="clear: both;"></div>
</div>

Demo

Well, that fixes very well, no collapsed parent anymore, but it adds unnecessary markup to the DOM, so some suggest, to use overflow: hidden; on the parent element holding floated child elements which work as intended.

Use overflow: hidden; on .wrapper

.wrapper {
    border: 3px solid green;
    overflow: hidden;
}

Demo

That saves us an element every time we need to clear float but as I tested various cases with this, it failed in one particular one, which uses box-shadow on the child elements.

Demo (Can't see the shadow on all 4 sides, overflow: hidden; causes this issue)

So what now? Save an element, no overflow: hidden; so go for a clear fix hack, use the below snippet in your CSS, and just as you use overflow: hidden; for the parent element, call the class below on the parent element to self-clear.

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

<div class="wrapper clear">
    <!-- Floated Elements -->
</div>

Demo

Here, shadow works as intended, also, it self-clears the parent element which prevents to collapse.

And lastly, we use footer after we clear the floated elements.

Demo

When is float: none; used anyways, as it is the default, so any use to declare float: none;?

Well, it depends, if you are going for a responsive design, you will use this value a lot of times, when you want your floated elements to render one below another at a certain resolution. For that float: none; property plays an important role there.

Few real-world examples of how float is useful.

The first example we already saw is to create one or more than one column layouts.
Using img floated inside p which will enable our content to flow around.

Demo (Without floating img)

Demo 2 (img floated to the left)

Using float for creating horizontal menu - Demo

Float second element as well, or use `margin`

Last but not the least, I want to explain this particular case where you float only single element to the left but you do not float the other, so what happens?

Suppose if we remove float: right; from our .floated_right class, the div will be rendered from extreme left as it isn't floated.

Demo

So in this case, either you can float the to the left as well

OR

You can use margin-left which will be equal to the size of the left floated column i.e 200px wide.

User · Answer

you can use overflow property to the container div if you don t have any div to show over the container eg    lt div class  cointainer  gt       lt div class  one  gt Content One lt  div gt       lt div class  two  gt Content Two lt  div gt   lt  div gt    Here is the following css    container      width 100     As per your requirment        height auto      float left      overflow hidden     one      width 200px    As per your requirment        height auto      float left      two      width 200px    As per your requirment        height auto      float left      -----------------------OR------------------------------       lt div class  cointainer  gt           lt div class  one  gt Content One lt  div gt           lt div class  two  gt Content Two lt  div gt           lt div class  clearfix  gt  lt  div gt       lt  div gt    Here is the following css        container          width 100     As per your requirment            height auto          float left          overflow hidden             one          width 200px    As per your requirment            height auto          float left              two          width 200px    As per your requirment            height auto          float left             clearfix before       clearfix after          display  table          content                  clearfix after          clear  both

User · Answer

Its because of the float of the div  Add overflow  hidden on the outside element    lt div style  overflow hidden  margin 0 auto width  960px  min-height  100px  background-color orange   gt       lt div style  width 500px  height 200px  background-color black  float right  gt       lt  div gt   lt  div gt    Demo

User · Answer

Try this one   parent div      display  flex

User · Answer

You need to add overflow auto to your parent div for it to encompass the inner floated div    lt div style  margin 0 auto width  960px  min-height  100px  background-color orange overflow auto  gt       lt div style  width 500px  height 200px  background-color black  float right  gt       lt  div gt   lt  div gt    jsFiddle example

User · Answer

You confuse how browsers renders the elements when there are floating elements  If one block element is floating  your inner div in your case   other block elements will ignore it because browser removes floating elements from the normal flow of the web page  Then  because the floated div has been removed from the normal flow  the outside div is filled in  like the inner div isn t there  However  inline elements  images  links  text  blackquotes  will respect the boundaries of the floating element  If you introduce text in the outside div  the text will place arround de inner div   In other words  block elements  headers  paragraphs  divs  etc  ignore floating elements and fill in  and inline elements  images  links  text  etc  respect boundaries of floating elements   An fiddle example here   lt body gt       lt div style  float right  background-color blue width 200px min-height 400px margin-right 20px  gt             floating element      lt  div gt       lt h1 style  background-color red   gt  this is a big header lt  h1 gt       lt p style  background-color green  gt  this is a parragraph with text and a big image  The text places arrounds the floating element  Because of the image is wider than space between paragrah and floating element places down the floating element  Try to make wider the viewport and see what happens  D          lt img src  http   2 bp blogspot com  nKxzQGcCLtQ TBYPAJ6xM4I AAAAAAAAAC8 lG6XemOXosU s1600 css png  gt        lt  p gt

User · Answer

You are encountering the float bug  though I m not sure if it s technically a bug due to how many browsers exhibit this behaviour    Here is what is happening   Under normal circumstances  assuming that no explicit height has been set  a block level element such as a div will set its height based on its content   The bottom of the parent div will extend beyond the last element   Unfortunately  floating an element stops the parent from taking the floated element into account when determining its height   This means that if your last element is floated  it will not  stretch  the parent in the same way a normal element would   Clearing  There are two common ways to fix this   The first is to add a  clearing  element  that is  another element below the floated one that will force the parent to stretch   So add the following html as the last child    lt div style  clear both  gt  lt  div gt    It shouldn t be visible  and by using clear both  you make sure that it won t sit next to the floated element  but after it   Overflow   The second method  which is preferred by most people  I think  is to change the CSS of the parent element so that the overflow is anything but  visible    So setting the overflow to  hidden  will force the parent to stretch beyond the bottom of the floated child   This is only true if you haven t set a height on the parent  of course   Like I said  the second method is preferred as it doesn t require you to go and add semantically meaningless elements to your markup  but there are times when you need the overflow to be visible  in which case adding a clearing element is more than acceptable

[html] Why doesn't the height of a container element increase if it contains floated elements?

How Does CSS Float Work?

What is float exactly and what does it do?

Float second element as well, or use `margin`

Examples related to html

Examples related to css

Examples related to css-float