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What is the z-index attribute?

藏色散人
藏色散人Original
2021-04-19 11:51:5120445browse

The z-index attribute is an attribute used in CSS to set the stacking order of elements. Elements with a higher stacking order will always be in front of elements with a lower stacking order, and elements can have negative The z-index attribute value.

What is the z-index attribute?

The operating environment of this article: Windows 7 system, Dell G3 computer, css3 version.

z-index attribute sets the stacking order of elements. Elements with a higher stacking order will always appear in front of elements with a lower stacking order.

Note: Elements can have negative z-index attribute values.

Note: Z-index only works on positioned elements (such as position:absolute;)!

Description

This property sets the position of a positioned element along the z-axis, which is defined as the axis that extends vertically to the display area. If it is a positive number, it is closer to the user, and if it is a negative number, it is further away from the user.

Default value: auto

Inheritance: no

Version: CSS2

JavaScript Syntax: object.style.zIndex="1"

Possible values

auto Default. The stacking order is equal to the parent element.

number Set the stacking order of elements.

inherit specifies that the value of the z-index attribute should be inherited from the parent element.

[Recommended learning: css video tutorial]

Example

Set the z-index of the image:

<html>
<head>
<style type="text/css">
img
{
position:absolute;
left:0px;
top:0px;
z-index:-1;
}
</style>
</head>

<body>
<h1>This is a heading</h1>
<img  src="/i/eg_smile.gif" / alt="What is the z-index attribute?" >
<p>由于图像的 z-index 是 -1,因此它在文本的后面出现。</p>
</body>
</html>

Effect:

What is the z-index attribute?

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