CSS高级教程CSS的定位属性和实例

CSS 定位 (Positioning)实例：
定位：相对定位   
本例演示如何相对于其正常位置来定位元素。   



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



This is a heading in normal position
This heading is moved left to its normal position
This heading is moved right to its normal position
Relative positioning moves an element RELATIVE to its original position.  
The style "left:-20px" subtracts 20 pixels from the element's original left position.  
The style "left:20px" adds 20 pixels to the element's original left position.  

  
定位：绝对定位   
本例演示如何使用绝对值来定位元素。  



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



This is a heading with an absolute position
With absolute positioning, an element can be placed anywhere on a page. The heading below is placed 100px from the left of the page and 150px from the top of the page.  

  
设置元素的形状   
本例演示如何设置元素的形状。此元素被剪入这个形状中，然后被显示出来。   



img
{
position:absolute;
clip:rect(0px 50px 200px 0px)
}



The clip property is here cutting an image:  

[img]bookasp20.gif[/img]
  

  
溢出   
本例演示当元素内容太大而超出规定区域时，如何设置溢出属性来规定相应的动作。   



div
{
background-color:#00FFFF;
width:150px;
height:150px;
overflow: scroll
}



The overflow property decides what to do if the content inside an element exceeds the given width and height properties.  

You can use the overflow property when you want to have better control of the layout. Try to change the overflow property to: visible, hidden, auto, or inherit and see what happens. The default value is visible.


  
垂直排列图象   
本例演示如何在文本中垂直排列图象。   



img.top {vertical-align:text-top}
img.bottom {vertical-align:text-bottom}




This is an

image inside a paragraph.
   

This is an

image inside a paragraph.
  

  
Z-index   
Z-index可被用于将在一个元素放置于另一元素之后。  



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



This is a Heading

[img]bulbon.gif[/img]

Default z-index is 0. Z-index -1 has lower priority.  

   
Z-index   
上面的例子中的元素已经更改了Z-index。  



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



This is a Heading

[img]bulbon.gif[/img]

Default z-index is 0. Z-index 1 has higher priority.  

  
CSS 定位属性 (Positioning)
CSS定位属性允许你对元素进行定位。  
浏览器支持：IE: Internet Explorer, F: Firefox, N: Netscape。  
W3C：“W3C”列的数字显示出定位(Positioning)属性由哪个CSS标准定义（CSS1还是CSS2）。  




Property
Description
Values
IE
F
N
W3C

bottom
设置元素的底边距离其父元素的底边之上或之下的距离。


auto
%
length
5
1
6
2

clip
设置元素的形状。元素被剪入这个形状之中，然后被显示出来。


shape
auto
4
1
6
2

left
设置元素的左边与其父元素的右边或左边的的距离。


auto
%
length
4
1
4
2

overflow
设置当元素内容溢出其区域时如何对内容进行管理


visible
hidden
scroll
auto
4
1
6
2

position
将元素放置于静态、相对、绝对或固定的位置


static
relative
absolute
fixed
4
1
4
2

right
设置元素的右边距父元素右边的左侧或右侧的距离


auto
%
length
5
1
6
2

top
设置元素的顶边距父元素的顶边的上方或下方的距离


auto
%
length
4
1
4
2

vertical-align
设置元素的垂直排列。


baseline
sub
super
top
text-top
middle
bottom
text-bottom
length
%
4
1
4
1

z-index
设置元素的堆叠顺序


auto
number
4
1
6
2