Why are use z-index in CSS explain with example?

Asked 19-Jul-2021
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Why are use z-index in CSS explain with example?

Ravi Vishwakarma
asked by Ravi Vishwakarma in web application
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2 Answers

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What is a Z Index?

Z Index (z-index) is a CSS property that defines the order of overlapping HTML elements. Elements with a higher index will be placed on top of elements with a lower index.

Note: Z index only works on positioned elements (position:absolute, position:relative, or position:fixed).

Possible Values

/* Default value if not specified */
z-index: auto;

/* Integer values */
z-index: 1;
z-index: 100;
z-index: 9999;
z-index: -1;

/* Global values */
z-index: inherit;
z-index: initial;
z-index: unset;

How to use the Z Index

In this example, you can see three boxes displayed on top of each other in different orders using z-index.

HTML

<div class='container'>
  <div class='box' id='blue'></div>
  <div class='box' id='red'></div>
  <div class='box' id='green'></div>
</div>

CSS

#blue {
  background-color: blue;
}

#red {
  background-color: red;
}

#green {
  background-color: green;
}

 

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Sanjay Goenka
answered 16-Jan-2023 by Sanjay Goenka

1

The z-index property stores any element in the order of the stack. Whichever element has higher stack order is shown first and whichever has a lower stack is shown below the higher element.

 Note:  z-index only works on positioned elements (absolute, relative, fixed, or sticky) and flex items (elements that are direct children of display: flex elements).

Example 

<!DOCTYPE html>

<html lang='en' xmlns='http://www.w3.org/1999/xhtml'>

<head>

    <meta charset='utf-8' />

    <title></title>

    <style>

        body {

            box-sizing: border-box;

            margin: 0px;

            padding: 0px;

        }

        div {

            border-radius:10px;

        }

        .center {

            display:flex;

            justify-content: center;

            width: 100%;

            align-items: center;

            height: 100vh;

            position:relative;

            text-align:center;

            font-weight:bold;

            font-size:25px;

        }

        #first {

            width: 80%;

            height: 80%;

            background-color: black;

            color: white;

            border: 1px solid black;

            z-index: 1;

            position:absolute;

        }

        #middle {

            z-index: 3;

            position:absolute;

            width: 60%;

            height: 60%;

            background-color: red;

            color: white;

            border: 1px solid red;

        }

        #last {

            z-index: 5;

            position:absolute;

            width: 40%;

            height: 40%;

            background-color: blue;

            color: white;

            border: 1px solid blue;

        }

    </style>

</head>

<body>

    <div class='center'>

        <div id='last'>Last div</div>

        <div id='middle'>middle div </div>

        <div id='first'>first div</div>

    </div>

</body>

</html>

    Why are use z-index in CSS explain with example?


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Ethan Karla
answered 07-Aug-2021 by Ethan Karla
MindStick Training