如何在div中垂直对齐div？

Question

Horizontally aligning a div-element within another div-element can be achived with margin: 0 auto; as long as they both have a width-property other than auto , but this does not apply for vertical alignment.

How can you vertically align a div within another div?

Answer 1

There are a number of different approaches to this, based on various ideas. Given that the element has a fixed height (in px, % or what have you), the best solution I've found so far is based on the following principle:

Give the parent div position: relative; and the child div position: absolute; , to make the child absolutley positioned in relation to the parent.

For the child, set top , bottom , left and right to 0 . Given that the child also has a fixed width and height that is less than the size of the parent, this will push the browser into an impossible situation.

In comes margin: auto; on the child, as the browsers savior. The browser can now add enough margin on all sides to let the child-element keep its size, yet still fill out the entire parent as forced by top , bottom , left and right set to 0 .

TADAAA! The element gets vertically and horizontally aligned within the parent.

Markup

<div class="parent">
    <div class="child"></div>
</div>

CSS

​.parent {
    width: 200px;
    height: 200px;
    position: relative;
}

.child {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    margin: auto;
    width: 100px;
    height: 100px;
}

A working example

http://jsfiddle.net/sg3Gw/

Answer 2

I find it easiest to use display:table-cell; vertical-align:middle; display:table-cell; vertical-align:middle; here's a jsfiddle

<style>
.a {
    border:1px solid red;
    width:400px;
    height:300px;
    display:table-cell;
    vertical-align:middle;
}
</style>
<div class="a">
    <div>CENTERED</div>
</div>
​