CSS z-index Property

The CSS z-index property specifies the z-order of an element and its descendants or flex items. The z-order is the order of elements on the z-axis.

The z-index of an element specifies its order inside a stacking context. A stacking context is a group of elements that have a common parent.

The element which has the higher stack order is in front of the element with a lower stack order. Elements having non-static positioning are on top of elements with default static positioning.

The z-index property affects only positioned elements that have a value other than “static”.
Initial Value auto
Applies to Positioned elements.
Inherited No.
Animatable Yes.
Version CSS2
DOM Syntax object.style.zIndex = "-1";

Syntax

z-index: auto | number | initial | inherit;

Example of the z-index property with a negative value:

<!DOCTYPE html>
<html>
  <head>
    <title>Title of the document</title>
    <style>
      img {
        position: absolute;
        left: 0;
        top: 10px;
        z-index: -1;
      }
    </style>
  </head>
  <body>
    <h2>Z-index property example</h2>
    <img src="/build/images/w3docs-logo-black.png" alt="W3docs logo" width="200" height="100">
  </body>
</html>

Example of the z-index property with a positive value:

<!DOCTYPE html>
<html>
  <head>
    <title>Title of the document</title>
    <style>
      #blue,
      #green,
      #grey {
        position: absolute;
        width: 150px;
        height: 150px;
        color: #eee;
        opacity: 0.95;
        padding: 15px;
        line-height: 100px;
        text-align: center;
      }
      #blue {
        z-index: 1;
        background-color: #1c87c9;
        top: 60px;
        left: 50px;
        line-height: 1;
      }
      .black {
        height: 80px;
        width: 160px;
        background-color: #000;
        line-height: 100px;
        bottom: 20px;
        position: absolute;
        z-index: 10;
      }
      #green {
        z-index: 2;
        background-color: #8ebf42;
        top: 100px;
        left: 170px;
      }
      #grey {
        background-color: #666;
        top: 200px;
        left: 100px;
      }
    </style>
  </head>
  <body>
    <h2>Z-index property example</h2>
    <div class="container">
      <div id="blue">
        Blue
        <div class="black">Black</div>
      </div>
      <div id="green">Green</div>
      <div id="grey">Grey</div>
    </div>
  </body>
</html>

Result

Values

Value Description Play it
auto The stack level of the generated box is equal to its parents. This is the default value of this property. Play it »
number The stack level of the generated box specified by numbers. Negative values are valid. Play it »
initial Makes the property use its default value. Play it »
inherit Inherits the property from its parents element.

Browser support

1.0+ 12.0+ 1.0+ 1.0+ 4.0+


Do you find this helpful?

Related articles