解决IE7 绝对定位z-index办法

作者：袖梨 2022-06-25
In IE7 browser, I just meet one issue about position. I made a demo page to test the position conditions of relative and absolute. There are the related codes below:
[CSS]

	  

		 代码如下
		复制代码
	  

	  

		.rela{ width:200px; height:100px; background:#EEE; margin-bottom:10px; position:relative; } .abs{ width:50px; height:50px; position:absolute; background:#333; left:20px; top:80px; z-index:10; }
[HTML]

	  

		 代码如下
		复制代码
	  

	  

		










	  

	
Now, the problem is, in IE7 browser, the "abs" element is covered by the next "rela" element, but it displays well in other browsers like Firefox, chrome, IE8. I know somebody said that we can add a more higher z-index to the parent "rela" element, but for the codes above, the issue can't be fixed in this condition, coz there are more than two rela elements and all of them have the abs element.
I have no idea about how to fix it now. Also, if someone could kindly provide a official explanation about this "bug", it will be so good.

enter image description here

其它参考

In short, try adding this CSS:

#envelope-1 {position:relative; z-index:1;}
or redesign the document such that your spans don't have position:relative any longer:

 代码如下 复制代码



    Z-Index IE7 Test
   


   


       

       
  • item
  • item
  • item
  • item

   

   


       
   


我们再精简一下：

XHTML部分：

 代码如下 复制代码


为什么负值的定位元素在IE和FF下显示不一致呢？Why？

CSS部分：

 代码如下 复制代码

#box1 { position: absolute; top: 100px; left: 210px; width: 200px; height: 200px; background-color: yellow; z-index: -10; }


大家会发现和上面没精简的代码显示的结果是一致的。但如果用上面的理解在IE下或许无法解释通。因为此时的理解背景色为黄色的box1的stacking context无论在FF下还是在IE下都是根元素产生的root stacking context。

迷惑：那么在IE浏览器中，按照规则，背景色为黄色的box1也应该消失，然而却没有。
解惑：IE浏览器似乎给body元素默认了一个相对定位属性（position: relative）。

通过上面两个简单的例子，我想大家应该大致知道为什么负值的z-index在IE和FF解析不一样，不是FF不支持，而是IE的BUG

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