CSS 绝对位置比固定位置具有更大的 z-index

Position absolute has greater z-index than position fixed

提问by dinodsaurus

I have a poblem with an element that is positioned relative. The problem is that I have a header with position fixed and content which is positioned relative. If I scroll down the content the element is put in front of the header. I tried with z-index but I just can't get it to work. I have put z-index:999on header.

我有一个相对定位的元素的问题。问题是我有一个位置固定的标题和相对定位的内容。如果我向下滚动内容，则该元素将放在标题前面。我尝试使用 z-index，但我无法让它工作。我已经把头z-index:999。

Here you can see my jsFiddle

在这里你可以看到我的jsFiddle

Here is a picture:

这是一张图片：

回答by Kevin Bowersox

The z-indexon the relative positioned element should be lower than the z-indexon the fixed position element. Here is a quick example:

的z-index相对定位的元件上应比下z-index固定位置元件上。这是一个快速示例：

HTML

HTML

<div id="fixed">Fixed Position</div>
<div id="relative">Relative Position</div>

CSS

CSS

body{
    height: 3000px;
}

#fixed{
    top: 0;
    height; 100px;
    background: green;
    width: 100%;
    position: fixed;
    z-index: 2;
}

#relative{
    position: relative;
    top: 100px;
    left: 50px;
    height: 100px;
    width: 100px;
    background: red;
    z-index: 1;
}

Working Example:http://jsfiddle.net/XZ4tM/1/

工作示例：http : //jsfiddle.net/XZ4tM/1/

Fixing Your Example

修正你的例子

The header styling has an issue, there are two colons ::proceeding the z-index properties value.

标题样式有问题，::z-index 属性值前有两个冒号。

  .header{
        width:960px;
        background: #43484A;
        height:80px;
        position: fixed;
        top:0;
        z-index: 9999; /* Removed extra : here */
   }

Fixed Examplehttp://jsfiddle.net/kUW66/2/

固定示例http://jsfiddle.net/kUW66/2/

回答by sanman

What I think you did is correct that using z-index in only a option. I have some work for you to understand.

我认为您所做的是正确的，仅在一个选项中使用 z-index。我有一些工作要你理解。

Please follow the JS Fiddle link

请按照JS Fiddle 链接

HTML

HTML

<div id="header">Header</div>
<div id="content1"><div id="content2"></div></div>

CSS

CSS

body{
    margin:0px auto;
    color:#FFF;
}
#header{
    background-color:#006666;
    width:100%;
    height:50px;
    position:fixed;
    text-align:center;
    font:bold 12px Arial, Helvetica, sans-serif;
    line-height:50px;
    display:block;
    z-index:10;
}
#content1{
    width:70%;
    height:1200px;
    margin:0px auto;
    background-color:#FFFF66;
    position:relative;
    top:50px;
    z-index:9;

}
#content2{
    width:50px;
    height:250px;
    margin:0px auto;
    background-color:#F60;
    postition:absolute;
    left:50px;
    top:50px;
}

Hope that helps.

希望有帮助。

回答by brunoais

"Content" is relative to the window, not the grey square.

“内容”相对于窗口，而不是灰色方块。

Did you try to make that grey square position:relative?

你有没有尝试制作那个灰色方块position:relative？

Without the HTML and the CSS, it's really hard to know the real cause.

没有 HTML 和 CSS，很难知道真正的原因。

回答by DiederikEEn

   .categories li{
        position:relative;
        z-index:-1;
        list-style: none;
        float:left;
        width:310px;
        height:310px;
        color:white;
        background:#77647F;
        margin-right:10px;
   }

check this fiddle :)HERE

检查这个小提琴 :)这里

I have changed the z-index to -1 to make it work.

我已将 z-index 更改为 -1 以使其工作。