Is it possible to set the stacking order of pseudo-elements below their parent element? [duplicate]

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后悔当初

2020-11-22 11:30
There are two issues are at play here:
1. The CSS 2.1 specification states that "The :beforeand :after pseudo-elements elements interact with other boxes, such as run-in boxes, as if they were real elements inserted just inside their associated element." Given the way z-indexes are implemented in most browsers, it's pretty difficult (read, I don't know of a way) to move content lower than the z-index of their parent element in the DOM that works in all browsers.
2. Number 1 above does not necessarily mean it's impossible, but the second impediment to it is actually worse: Ultimately it's a matter of browser support. Firefox didn't support positioning of generated content at all until FF3.6. Who knows about browsers like IE. So even if you can find a hack to make it work in one browser, it's very likely it will only work in that browser.
The only thing I can think of that's going to work across browsers is to use javascript to insert the element rather than CSS. I know that's not a great solution, but the :before and :after pseudo-selectors just really don't look like they're gonna cut it here.
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后悔当初

2020-11-22 11:31
I fixed it very simple:
```
.parent {
  position: relative;
  z-index: 1;
}

.child {
  position: absolute;
  z-index: -1;
}
```
What this does is stack the parent at z-index: 1, which gives the child room to 'end up' at z-index: 0 since other dom elements 'exist' on z-index: 0. If we don't give the parent an z-index of 1 the child will end up below the other dom elements and thus will not be visible.

This also works for pseudo elements like :after
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余生分开走

2020-11-22 11:36

I know this is an old thread, but I feel the need to post the proper answer. The actual answer to this question is that you need to create a new stacking context on the parent of the element with the pseudo element (and you actually have to give it a z-index, not just a position).

Like this:

#parent {
    position: relative;
    z-index: 1;
}
#pseudo-parent {
    position: absolute;
    /* no z-index allowed */
}
#pseudo-parent:after {
    position: absolute;
    top:0;
    z-index: -1;
}

It has nothing to do with using :before or :after pseudo elements.

#parent { position: relative; z-index: 1; }
#pseudo-parent { position: absolute; } /* no z-index required */
#pseudo-parent:after { position: absolute; z-index: -1; }

/* Example styling to illustrate */
#pseudo-parent { background: #d1d1d1; }
#pseudo-parent:after { margin-left: -3px; content: "M" }

<div id="parent">
 <div id="pseudo-parent">
   &nbsp;
 </div>
</div>

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广开言路

2020-11-22 11:37

Set the z-index of the :before or :after pseudo element to -1 and give it a position that honors the z-index property (absolute, relative, or fixed). This works because the pseudo element's z-index is relative to its parent element, rather than <html>, which is the default for other elements. Which makes sense because they are child elements of <html>.

The problem I was having (that lead me to this question and the accepted answer above) was that I was trying to use a :after pseudo element to get fancy with a background to an element with z-index of 15, and even when set with a z-index of 14, it was still being rendered on top of its parent. This is because, in that stacking context, it's parent has a z-index of 0.

Hopefully that helps clarify a little what's going on.

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青春惊慌失措

2020-11-22 11:38
I don't know if someone will have the same issue with this. The selected answer is partially correct.

What you need to have is:
```
parent{
  z-index: 1;
}
child{
 position:relative;
 backgr
```
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说谎

2020-11-22 11:43

I know this question is ancient and has an accepted answer, but I found a better solution to the problem. I am posting it here so I don't create a duplicate question, and the solution is still available to others.

Switch the order of the elements. Use the :before pseudo-element for the content that should be underneath, and adjust margins to compensate. The margin cleanup can be messy, but the desired z-index will be preserved.

I've tested this with IE8 and FF3.6 successfully.

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