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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.

Try it

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: revert;
z-index: revert-layer;
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 0.
<integer>: This <integer> is the stack level of the generated box in the current stacking context. The box also establishes a local stacking context. 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

z-index = 
  auto       |
  <integer>  |
  inherit

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
Cascading Style Sheets Level 2 Revision 2 (CSS 2.2) Specification # z-index

Browser compatibility

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	WebView Android	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet
`z-index`	1	12	1	4	4	1	≤37	18	4	14	1	1.0
`negative_values`	1	12	3	4	4	1	≤37	18	4	14	1	1.0