Why doesn't the height of a container element increase if it contains floated elements?
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:
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 doesfloat
do? Initially, thefloat
property was introduced to flow text around images, which are floatedleft
orright
. 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 thefloat
property in order to set boxes side by side.Floating an
Demoinline
orblock
level element will make the element behave like aninline-block
element.If you float an element
left
orright
, thewidth
of the element will be limited to the content it holds, unlesswidth
is defined explicitly ...You cannot
float
an elementcenter
. This is the biggest issue I've always seen with beginners, using, which is not a valid value for thefloat: center;
float
property.float
is generally used tofloat
/move content to the very left or to the very right. There are only four valid values forfloat
property i.eleft
,right
,none
(default) andinherit
.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;
orfloat: 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 toz-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...
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 toclear
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 insidep
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.
How to make a div grow in height while having floats inside
overflow:auto;
on the containing div makes everything inside of it (even floated items) visible and the outer div fully wraps around them. See this example:
.wrap { padding: 1em; overflow: auto; background: silver; } .float { float: left; width: 40%; background: white; margin: 0 1%;}
<div class="wrap"> <div class="float">Cras mattis iudicium purus sit amet fermentum. At nos hinc posthac, sitientis piros Afros. Qui ipsorum lingua Celtae, nostra Galli appellantur. Petierunt uti sibi concilium totius Galliae in diem certam indicere. Ambitioni dedisse scripsisse iudicaretur.</div> <div class="float">Mercedem aut nummos unde unde extricat, amaras. A communi observantia non est recedendum. Quisque ut dolor gravida, placerat libero vel, euismod. Paullum deliquit, ponderibus modulisque suis ratio utitur.</div> </div>
Floating image to the left changes container div's height
Add overflow:auto;
to #container
(Explanations below)
Floated elements of variable height push siblings down
How about a CSS only solution? Add this rule:
figure:nth-of-type(3n+1) {
clear:left;
}
jsFiddle example
Float multiple fixed-width / varible-height boxes into 2 columns
You need to alternate left and right floating on your boxes.
.box:nth-child(2n+1){
float: left;
}
.box:nth-child(2n){
float: right;
}
Warning this code is not compatible with older browsers, for those you might want to set a different CSS classes programmatically every other box.
different height divs float in two columns
You're going to have to do this with JavaScript. If you're using jQuery, there is an excellent plugin called Masonry. There is also the non jQuery version.
To quote the README on GitHub:
Masonry is a dynamic grid layout script. Think of it as the flip-side
of CSS floats. Whereas floating arranges elements horizontally then
vertically, Masonry arranges elements vertically, positioning each
element in the next open spot in the grid. The result minimizes
vertical gaps between elements of varying height, just like a mason
fitting stones in a wall.
The single column layout is probably what you're looking for.
If you don't mind leaving older browsers in the dust, there are the CSS3 column
properties. There's an example here, on Quirksmode, and some documentation on the MDN.
Height of a container with floating children
Set overflow:auto
on the containing div:
<div style='background:#ccc;overflow:auto;'> <ul> <li style='display:block; float:left; width:50%;'> item 1 </li> <li style='display:block; float:left; width:50%;'> item 2 </li> <li style='display:block; float:left; width:50%;'> item 3 </li> <li style='display:block; float:left; width:50%;'> item 4 </li> <li style='display:block; float:left; width:50%;'> item 5 </li> <li style='display:block; float:left; width:50%;'> item 6 </li> </ul></div>
Float divs with variable heights (arrange)
I don't think that this is doable a 100% with "just" css, but jquery-masonry should do the trick [ http://desandro.com/resources/jquery-masonry/ ]. Well, but i hope somebody proofs me wrong :)
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