You can use the z-index property in CSS to help you control which element should appear at the top of others on a webpage. But sometimes it might not work. This blog will be helpful if you have faced issues like overlapping elements incorrectly or ignoring your z-index settings. You can figure it out and fix it with the solutions given below.
Table of Contents:
Understanding z-index and Stacking Context
You should understand the workings of z-index before you start fixing the issue.
What is z-index?
You can use the z-index property in CSS to stack the elements on top of others. You can see the elements with a higher z-index come first than the lower ones.
Syntax:
.element1 {
position: absolute;
z-index: 1;
}
.element2 {
position: absolute;
z-index: 2;
}
The .element2 will show up in front of .element1 because it has a higher z-index value.
What is Stacking?
A stacking context is like a group of elements with special stacking rules. You can create when the element has properties like position: relative, position: absolute, position: fixed, opacity less than 1, transform, filter, or will-change.
When the new stacking rules are made, the child elements inside it stay within that context, and that cannot be broken. This is the reason why z-index might not work.
Common Reasons and Solutions
There are a few reasons why z-index is not working. Let us discuss these reasons with the solution:
Reason 1: The Element Lacks a Positioning Context
You can use the z-index property to work on the element that is set to position, like relative, absolute, or fixed. If the position is position: static by default, z-index won’t work.
Solution:
<!DOCTYPE html>
<html>
<head>
<style>
.box1 {
position: relative;
width: 200px;
height: 200px;
background-color: red;
z-index: 1;
}
.box2 {
position: relative;
width: 200px;
height: 200px;
background-color: blue;
margin-top: -100px;
z-index: 2;
}
</style>
</head>
<body>
<div class="box1"></div>
<div class="box2"></div>
</body>
</html>
Output:
Explanation: You can get two overlapping boxes from this code. Box 1(red) is placed first with z-index: 1, and box 2(blue) overlaps it using margin-top: -100px, which appears in front with z-index: 2. You can use relative positioning for proper stacking.
Reason 2: Parent’s Stacking Context is Overriding the z-index
You can see the element that is inside a parent that creates a stacking context, and the z-index will depend parent instead of the whole document.
Solution:
<!DOCTYPE html>
<html>
<head>
<style>
.parent {
position: relative;
z-index: 1;
background-color: lightgray;
padding: 20px;
}
.child {
position: absolute;
width: 100px;
height: 100px;
background-color: green;
z-index: 2;
}
</style>
</head>
<body>
<div class="parent">
Parent Div
<div class="child">Child Box</div>
</div>
</body>
</html>
Output:
Explanation: The parent element (light grey box) creates a stacking context with relative positioning and z-index: 1. The child element (green box), with absolute positioning and z-index: 2, appears on top within this context.
Reason 3: Negative z-index Values Can Be Problematic
If you use a negative z-index, it moves the element behind other content. However, it could get hidden behind the body background if its parent element doesn’t support negative stacking.
Solution:
<!DOCTYPE html>
<html>
<head>
<style>
.parent {
position: relative;
}
.child {
position: absolute;
z-index: -1;
background-color: yellow;
width: 100px;
height: 100px;
}
</style>
</head>
<body>
<div class="parent">
<div class="child">Behind Parent</div>
</div>
</body>
</html>
Output:
Explanation: This code creates a parent element and a child element. The child (yellow box) has absolute positioning and a z-index: -1, which places it behind the parent element. Since the parent has relative positioning, it establishes a stacking context.
Reason 4: Fixed Position Elements
When you use position: fixed, the element is removed from the regular document layout and usually shows up on top of other elements.
Solution:
You should set an appropriate z-index for both elements.
<!DOCTYPE html>
<html>
<head>
<style>
.fixed-box {
position: fixed;
top: 50px;
left: 50px;
width: 150px;
height: 150px;
background-color: orange;
z-index: 1000;
}
</style>
</head>
<body>
<div class="fixed-box">Fixed Box</div>
</body>
</html>
Output:
Explanation: You can create a box in a fixed position on the screen using this code. You can use top: 50px and left: 50px to place it 50 pixels away from the top-left corner. The z-index: 1000 makes it appear on top of other elements.
Conclusion
You can use z-index to control which elements appear on top. This only works if the element has a relative, absolute, or fixed position. The new stacking rules by the parent element make z-index values override child elements. The negative z-index values can hide elements if it is unsupported by the parent. You should have a better understanding of stacking rules to resolve these issues effectively.
Why is z-index Not Working? – FAQs
1. Why isn't z-index working on my element?
z-index only works on elements with position: relative, absolute, or fixed. If your element has position: static (default), z-index won’t apply.
2.Why is my z-index value being ignored?
A parent element may have created a new stacking context, which limits how z-index works for child elements.
3. Why is my negative z-index hiding the element?
A negative z-index can push an element behind others, but it may also disappear behind the body background if the parent doesn’t support negative stacking.
4. Why is a fixed-position element always on top?
Fixed elements are often removed from the normal document flow, so their z-index needs to be adjusted for proper stacking.
5. How can I fix z-index issues caused by stacking contexts?
Check the parent elements for properties like opacity, transform, or filter, which might create stacking contexts, and adjust their z-index accordingly.