Web/CSS/z-index

The z-index CSS property sets the z-order of a positioned element and its descendants or flex items. Overlapping elements with a larger z-index cover those with a smaller one.

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For a positioned box (that is, one with any position other than static), the z-index property specifies:

The stack level of the box in the current stacking context.
Whether the box establishes a local stacking context.

Syntax

/* Keyword value */
z-index: auto;

/* <integer> values */
z-index: 0;
z-index: 3;
z-index: 289;
z-index: -1; /* Negative values to lower the priority */

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

The z-index property is specified as either the keyword auto or an <integer>.

Values

auto: The box does not establish a new local stacking context. The stack level of the generated box in the current stacking context is the same as its parent's box.
<span id="<integer>"><integer>: This <integer> is the stack level of the generated box in the current stacking context. The box also establishes a local stacking context in which its stack level is 0. This means that the z-indexes of descendants are not compared to the z-indexes of elements outside this element.

Formal definition

Initial value	`auto`
Applies to	positioned elements
Inherited	no
Computed value	as specified
Animation type	an integer
Creates stacking context	yes

Formal syntax

auto | <integer>

Examples

Visually layering elements

HTML

<div class="wrapper">
  <div class="dashed-box">Dashed box</div>
  <div class="gold-box">Gold box</div>
  <div class="green-box">Green box</div>
</div>

CSS

.wrapper {
  position: relative;
}

.dashed-box { 
  position: relative;
  z-index: 1;
  border: dashed;
  height: 8em;
  margin-bottom: 1em;
  margin-top: 2em;
}
.gold-box { 
  position: absolute;
  z-index: 3; /* put .gold-box above .green-box and .dashed-box */
  background: gold;
  width: 80%;
  left: 60px;
  top: 3em;
}
.green-box { 
  position: absolute;
  z-index: 2; /* put .green-box above .dashed-box */
  background: lightgreen;
  width: 20%;
  left: 65%;
  top: -25px;
  height: 7em;
  opacity: 0.9;
}

Result

Specifications

Specification	Status	Comment
CSS Level 2 (Revision 1)The definition of 'z-index' in that specification.	Recommendation	Initial definition

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`z-index`	Chrome Full support 1	Edge Full support 12	Firefox Full support 1	IE Full support 4	Opera Full support 4	Safari Full support 1	WebView Android Full support ≤37	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 14	Safari iOS Full support 1	Samsung Internet Android Full support 1.0
Negative values	Chrome Full support 1	Edge Full support 12	Firefox Full support 3	IE Full support 4	Opera Full support 4	Safari Full support 1	WebView Android Full support ≤37	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 14	Safari iOS Full support 1	Samsung Internet Android Full support 1.0

Legend

Full support: Full support