Z-Index with different parents

问题

I'm having some trouble with the z-index. This is my simplified layout:

<div id="overlapper"></div>
<div id="container">
    <div id="child1"></div>
    <div id="child2"></div>
</div>

I need overlapper to appear in front of child1 but behind child2. I tried messing around with z index but it didn't work, I think because of the stacking context.

Any help please? thanks

回答1:

First, make sure that overlapper, child1 and child2 belong to the same stacking context.

That is, make sure container doesn't create a stacking context:

container must not be the root element.
container must have the default value for position, z-index, opacity and isolation properties:
- position: static or z-index: auto
- opacity: 1
- isolation: auto

Now, make overlapper, child1 and child2 positioned elements, and add z-index as you want.

#overlapper, #child1, #child2 {
  position: relative;
  padding: 30px;
  height: 20px;
}
#overlapper {
  z-index: 3;
  background: red;
  top: 60px;
  margin-left: 20px;
}
#container {
  margin-top: -40px;
}
#child1 {
  z-index: 2;
  background: green;
  top: -40px;
}
#child2 {
  z-index: 4;
  background: blue;
  margin-left: 40px;
}

<div id="overlapper">Overlapper</div>
<div id="container">
    <div id="child1">Child 1</div>
    <div id="child2">Child 2</div>
</div>

回答2:

HTML

<div id="overlapper"></div>
<div id="container">
    <div id="child1"></div>
    <div id="child2"></div>
</div>

CSS

#overlapper, #child1, #child2
{
    height: 100px;
    width: 100px;
    position: absolute;
}
#overlapper
{
    background: red;
    top : 40px;
    left : 40px;
    z-index: 1;
}
#child1
{
    background: yellow;
    z-index: 0;
}
#child2
{
    top: 60px;
    left : 60px;
    background: black; 
    z-index: 2;
}

Fidle Here

来源：https://stackoverflow.com/questions/27329962/z-index-with-different-parents

标签

html

css

z-index