How to Position a Child Element Above Its Parent Using z-index in CSS?

Raising Child Element Above Parent Using z-Index

In HTML, elements follow a hierarchical structure called the Document Object Model (DOM). When multiple overlapping elements exist, their z-index property determines which one is displayed on top.

Consider the following HTML code:

<div class="parent">
    <div class="child">
        Hello world
    </div>
</div>

<div class="wholePage"></div>

Suppose you want the "child" div to appear above the "wholePage" div. However, by default, the "parent" div's z-index affects all its child elements.

// Wrong approach
.parent {
  z-index: 100;
  position: relative;
}

// Incorrect output: "child" is hidden behind "wholePage"

Solution:

As mentioned in the answer provided, it's impossible to set a child's z-index higher than its parent's using only CSS. However, there are two workarounds:

1. Remove z-index from Parent:

Remove the z-index property from the "parent" div:

.parent {
  position: relative;
}

This allows the "child" div to inherit its own z-index, which can be set to be higher than "wholePage".

2. Make Sibling Instead of Child:

Instead of being a child of the "parent" div, make the "child" div a sibling of "wholePage" and set its z-index accordingly:

<div class="sibling">
    <div class="child">
        Hello world
    </div>
</div>

<div class="wholePage"></div>

.sibling {
  position: absolute;
  z-index: 100;
}

.child {
  position: absolute;
  z-index: 150;
}

In this case, both "child" and "wholePage" are siblings, and the "child" div's higher z-index ensures it appears on top. Note that using "position: absolute;" instead of "position: relative;" in this context allows the child to be positioned outside its parent's flow.

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