CSS positioning

kaqi

浏览: 228165 次
性别:
来自: 北京

最近访客更多访客>>

一个java程序员

sqllib

邱理军

weixuan

博主相关

博客

微博

相册

留言

关于我

文章分类

社区版块

存档分类

博客分类：

Positioning

The CSS positioning properties allow you to position an element. It can also place an element behind another, and specify what should happen when an element's content is too big.

Elements can be positioned using the top, bottom, left, and right properties. However, these properties will not work unless the position property is set first. They also work differently depending on the positioning method.

There are four different positioning methods.

Static Positioning

HTML elements are positioned static by default. A static positioned element is always positioned according to the normal flow of the page.

Static positioned elements are not affected by the top, bottom, left, and right properties.

Fixed Positioning

An element with fixed position is positioned relative to the browser window.

It will not move even if the window is scrolled:

Example

p.pos_fixed
{
position:fixed;
top:30px;
right:5px;
}

Try it yourself »

Note: IE7 and IE8 support the fixed value only if a !DOCTYPE is specified.

Fixed positioned elements are removed from the normal flow. The document and other elements behave like the fixed positioned element does not exist.

Fixed positioned elements can overlap other elements.

Relative Positioning

A relative positioned element is positioned relative to its normal position.

Example

h2.pos_left
{
position:relative;
left:-20px;
}
h2.pos_right
{
position:relative;
left:20px;
}

Try it yourself »

The content of relatively positioned elements can be moved and overlap other elements, but the reserved space for the element is still preserved in the normal flow.

Example

h2.pos_top
{
position:relative;
top:-50px;
}

Try it yourself »

Relatively positioned elements are often used as container blocks for absolutely positioned elements.

Absolute Positioning

An absolute position element is positioned relative to the first parent element that has a position other than static. If no such element is found, the containing block is <html>:

Example

h2
{
position:absolute;
left:100px;
top:150px;
}

Try it yourself »

Absolutely positioned elements are removed from the normal flow. The document and other elements behave like the absolutely positioned element does not exist.

Absolutely positioned elements can overlap other elements.

Overlapping Elements

When elements are positioned outside the normal flow, they can overlap other elements.

The z-index property specifies the stack order of an element (which element should be placed in front of, or behind, the others).

An element can have a positive or negative stack order:

Example

img
{
position:absolute;
left:0px;
top:0px;
z-index:-1
}

Try it yourself »

An element with greater stack order is always in front of an element with a lower stack order.

Note: If two positioned elements overlap, without a z-index specified, the element positioned last in the HTML code will be shown on top.

分享到：

mac os terminal hot key | CSS Display - Block and Inline Elements, ...

2011-12-19 22:23
浏览 582
评论(0)
分类:Web前端
查看更多

发表评论

您还没有登录,请您登录后再发表评论

最近访客更多访客>>

博主相关

文章分类

社区版块

存档分类

最新评论

CSS positioning

Positioning

Static Positioning

Fixed Positioning

Example

Relative Positioning

Example

Example

Absolute Positioning

Example

Overlapping Elements

Example

评论

发表评论

相关推荐

最近访客 更多访客>>

博主相关

文章分类

社区版块

存档分类

最新评论

CSS positioning

Positioning

Static Positioning

Fixed Positioning

Example

Relative Positioning

Example

Example

Absolute Positioning

Example

Overlapping Elements

Example

评论

发表评论

相关推荐

The 30 CSS Selectors you Must Memorize

Link up background image

Simple switch themes

Pull common style up

Element With Attachment

Navigation with ul and li

Clear floated elements

Columns With Relative Width

Blocked Wrapper

Required red star

Overlapped Margins

Padding Images With Background Image

Full Screen Page Width

Fixed Pixels Page Width

CSS Reset

Vertically Centering With Line-Height

Padding Images With Absolute Position

Horizontally centering with "margin auto"

Wrap the line in pre

hover on one part, display another part on page by CSS

最近访客更多访客>>